Method of forming pattern

ABSTRACT

Provided is a method of forming pattern including (a) forming a chemically amplified resist composition into a film, (b) exposing the film to light, and (c) developing the exposed film with a developer containing a first organic solvent, wherein in the developer, particles each having a diameter of 0.3 μm or greater amount to a density of 30 particles/ml or less.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2010-188639, filed Aug. 25, 2010,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of forming a pattern. Moreparticularly, the present invention relates to a method of forming apattern that is suitable for use in, for example, a semiconductorproduction process for an IC or the like, a circuit board productionprocess for a liquid crystal, a thermal head or the like and otherphotoapplication lithography processes. In particular, the presentinvention relates to a method of forming a pattern that is suitable forthe lithography using an ArF exposure apparatus or liquid-immersionprojection exposure apparatus in which a far-ultraviolet light ofwavelength 300 nm or shorter is employed as a light source.

2. Description of the Related Art

Since the development of the resist for a KrF excimer laser (248 nm), apattern forming method based on chemical amplification has been employedas a resist patterning method in order to compensate for any sensitivitydecrease caused by light absorption. A positive pattern forming methodbased on chemical amplification will be described by way of example. Inthis pattern forming method, the acid generator contained in exposedareas is decomposed upon exposure to light, such as an excimer laser,electron beams or an extreme ultraviolet light, to thereby generate anacid. In the stage of the bake after the exposure (Post-Exposure Bake:PEB), the generated acid is utilized as a reaction catalyst so thatalkali-insoluble groups are converted to alkali-soluble groups.Thereafter, the exposed areas are removed by an alkali developer.

For use in the above method, various alkali developers have beenproposed. For example, an aqueous alkali developer containing 2.38 mass% TMAH (aqueous solution of tetramethylammonium hydroxide) isuniversally used.

Moreover, the shortening of the wavelength of exposure light sources andthe realization of high numerical apertures (high NA) for projectorlenses have been advanced in order to cope with the miniaturization ofsemiconductor elements. To now, an exposure unit using an ArF excimerlaser of 193 nm wavelength as a light source has been developed.Further, a method, known as a liquid-immersion method, in which thespace between a projector lens and a sample is filled with a liquid ofhigh refractive index (hereinafter also referred to as an “immersionliquid”) has been proposed as a technology for enhancing the resolvingpower. Still further, an EUV lithography or the like in which exposureis carried out using an ultraviolet of further shorter wavelength (13.5nm) has been proposed.

In another aspect, not only the currently mainstream positive type butalso negative chemically amplified resist compositions for use in thepattern formation by alkali development are being developed (see, forexample, patent references 1 to 4). This reflects the situation in whichin the production of semiconductor elements and the like, while there isa demand for the formation of a pattern with various configurations,such as a line, a trench and a hole, there exist patterns whoseformation is difficult with the use of current positive resists.

Also, the development of negative resist developers is being promoted.For example, patent reference 5 discloses using as a developer anegative developer comprising an organic solvent in which the content ofmetal impurities is controlled at a given value or less in order torealize a pattern formation exhibiting a high sensitivity, excelling inthe resolution of trench pattern and ensuring favorable iso/dense bias.

Moreover, a double development technique as a double patterningtechnology capable of enhancing the resolving power is described inpatent reference 6 and patent reference 7. In this technique, using thephenomenon that upon exposure, the polarity of the resin contained inthe resist composition becomes high in a region of high light intensitywhile the polarity of the resin is kept low in a region of low lightintensity, the region of high exposure in a specified resist film isdissolved by a developer of high polarity while the region of lowexposure is dissolved by a developer comprising an organic solvent.Thus, the region of intermediate exposure amount remains undissolvedaway during the development, so that a line-and-space pattern with ahalf pitch of exposure mask is formed.

CITATION LIST Patent Literature

-   [Patent reference 1] Jpn. Pat. Appln. KOKAI Publication No.    (hereinafter referred to as JP-A-) 2006-317803,-   [Patent reference 2] JP-A-2006-259582,-   [Patent reference 3] JP-A-2006-195050,-   [Patent reference 4] JP-A-2000-206694,-   [Patent reference 5] JP-A-2009-025708,-   [Patent reference 6] JP-A-2008-292975, and-   [Patent reference 7] JP-A-2010-152353.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method of forminga pattern by which a pattern of low defect density can be formed.

The present invention is, for example, as follows.

Herein, the term “particle density” refers to the value measured bymeans of an in-liquid particle sensor KS-41A (manufactured by Rion Co.,Ltd.). In particular, the number of particles each having a diameter of0.3 μm or greater is counted by means of this instrument, and the numberis divided by the volume of the fluid used in the measurement. Thus, the“particle density (number/ml)” is determined.

[1] A method of forming a pattern, comprising:

-   -   (a) forming a chemically amplified resist composition into a        film,    -   (b) exposing the film to light, and    -   (c) developing the exposed film with a developer containing a        first organic solvent,

wherein in the developer, particles each having a diameter of 0.3 μm orgreater amount to a density of 30 particles/ml or less.

[2] The method according to item [1], wherein the first organic solventcontained in the developer is one filled in a storage container in anenvironment whose cleanliness defined in US Federal Standard (USA Fed.Std.) 209E is class 10,000 or below.

[3] The method according to item [1] or [2], which further comprises:

-   -   (d) rinsing the developed film by a rinse liquid containing a        second organic solvent,

wherein in the rinse liquid, particles each having a diameter of 0.3 μmor greater amount to a density of 30 particles/ml or less.

[4] The method according to item [3], wherein the second organic solventcontained in the rinse liquid is one filled in a storage container in anenvironment whose cleanliness defined in US Federal Standard (USA Fed.Std.) 209E is class 10,000 or below.

[5] The method according to any one of items [1] to [4], wherein theexposure (b) is carried out using an ArF excimer laser.

[6] The method according to any one of items [1] to [5], wherein thecomposition comprises a resin containing a group that when acted on byan acid, is decomposed to thereby produce a polar group and a compoundthat when exposed to actinic rays or radiation, generates an acid.

[7] The method according to item [6], wherein the resin has an alicyclichydrocarbon structure.

[8] The method according to item [6] or [7], wherein substantially noaromatic ring is contained in the resin.

[9] A developer containing an organic solvent, wherein particles eachhaving a diameter of 0.3 μm or greater are contained in a density of 30particles/ml or less, for use in the method according to any one ofitems [1] to [8].

[10] A rinse liquid containing an organic solvent, wherein particleseach having a diameter of 0.3 μm or greater are contained in a densityof 30 particles/ml or less, for use in the method according to any oneof items [3] to [8].

The present invention has made it feasible to provide a method offorming a pattern by which a pattern of low defect density can beformed.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described in detail below.

Herein, the groups and atomic groups for which no statement is made asto substitution or nonsubstitution are to be interpreted as includingthose containing no substituents and also those containing substituents.For example, the “alkyl groups” for which no statement is made as tosubstitution or nonsubstitution are to be interpreted as including notonly the alkyl groups containing no substituents (unsubstituted alkylgroups) but also the alkyl groups containing substituents (substitutedalkyl groups).

Further, herein, the terms “actinic rays” and “radiation” mean, forexample, brightline spectra from a mercury lamp, far ultravioletrepresented by an excimer laser, extreme ultraviolet (EUV), X-rays andelectron beams (EB). The term “light” means actinic rays or radiation.The term “exposure” means not only irradiation with light, such as lightfrom a mercury lamp, far ultraviolet, X-rays or EUV light, but alsolithography using particle beams, such as electron beams and ion beams.

Heretofore, a method comprising (a) forming a chemically amplifiedresist composition into a film, (b) exposing the film to light and (c)developing the exposed film with a developer containing an organicsolvent is known as a negative patterning method.

The inventors have found that the defect density of the pattern islikely to become relatively high when a pattern is formed by thismethod. The reason therefor is not necessarily apparent. However, theinventors have arrived at the following further finding.

Namely, in the positive patterning method using an alkali developer, thepattern remaining after the development is hydrophobic. In contrast, inthe negative patterning method using a developer containing an organicsolvent, the pattern remaining after the development is hydrophilic.Accordingly, in the latter instance, the pattern remaining after thedevelopment has polarity. Therefore, in this instance, particles derivedfrom the developer are likely to adhere onto the pattern having beenformed or being formed. Consequently, in this instance, there is thepossibility of increasing of the defect density of the pattern caused byparticles being present in the developer.

Taking these aspects into account, the inventors have studied the use ofa developer with the following formulation. Consequently, the inventorshave proved that the defect density of the pattern can be strikinglyreduced by employing the following formulation.

[1] Developer and Rinse Liquid

In the developer containing an organic solvent for use in the method ofthe present invention, the density of particles each having a diameterof 0.3 μm or greater is 30 particles/ml or less. The particle density ispreferably 25 particles/ml or less, more preferably 20 particles/ml orless, further more preferably 15 particles/ml or less, still furthermore preferably 10 particles/ml or less and most preferably 5particles/ml or less.

As the means for regulating the particle density of the developercontaining an organic solvent so as to fall within the above ranges,there can be mentioned, for example, the following methods. Two or moreof these methods may be used in combination.

(1) As the organic solvent contained the developer, use is made of onehaving been passed through a filter with a small pore size. The filteris preferably a polyethylene filter. The pore size of the filter ispreferably 0.10 μm or less, more preferably 0.05 μm or less.

(2) As the organic solvent contained in the developer, use is made ofone filled in a storage container in an environment whose cleanlinessdefined in US Federal Standard (USA Fed. Std.) 209E is class 10,000 orbelow. This filling is preferably performed in an environment whosecleanliness is class 1000 or below, more preferably an environment whosecleanliness is class 100 or below.

(3) As the organic solvent contained in the developer, use is made ofone filled in a storage container having been rinsed with the aboveorganic solvent and dried.

(4) As the organic solvent contained in the developer, use is made ofone having been subjected to distilling operation.

As the developers containing an organic solvent, there can be mentioned,for example, developers containing a polar solvent, such as a ketonesolvent, an ester solvent, an alcohol solvent, an amide solvent or anether solvent, and a hydrocarbon solvent.

As the ketone solvent, there can be mentioned, for example, 1-octanone,2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone,2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone,phenylacetone, methyl ethyl ketone, methyl isobutyl ketone,acetylacetone, acetonylacetone, ionone, diacetonyl alcohol,acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone orpropylene carbonate.

As the ester solvent, there can be mentioned, for example, methylacetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate,propylene glycol monomethyl ether acetate, ethylene glycol monoethylether acetate, diethylene glycol monobutyl ether acetate, diethyleneglycol monoethyl ether acetate, ethyl 3-ethoxypropionate (EEP),3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate,ethyl formate, butyl formate, propyl formate, ethyl lactate, butyllactate, propyl lactate, methyl propionate, ethyl propionate or propylpropionate. In particular, acetic acid alkyl esters, such as methylacetate, butyl acetate, ethyl acetate, isopropyl acetate and amylacetate, and propionic acid alkyl esters, such as methyl propionate,ethyl propionate and propyl propionate, are preferred.

As the alcohol solvent, there can be mentioned, for example, an alcohol,such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropylalcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol,isobutyl alcohol, n-hexyl alcohol, 4-methyl-2-pentanol, n-heptylalcohol, n-octyl alcohol or n-decanol; a glycol, such as ethyleneglycol, diethylene glycol or triethylene glycol; or a glycol ether, suchas ethylene glycol monomethyl ether, propylene glycol monomethyl ether,ethylene glycol monoethyl ether, propylene glycol monoethyl ether,diethylene glycol monomethyl ether, triethylene glycol monoethyl etheror methoxymethylbutanol.

As the ether solvent, there can be mentioned, for example, not only anyof the above-mentioned glycol ethers but also dioxane, tetrahydrofuranor the like.

As the amide solvent, there can be mentioned, for example,N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide,hexamethylphosphoric triamide or 1,3-dimethyl-2-imidazolidinone.

As the hydrocarbon solvent, there can be mentioned, for example, anaromatic hydrocarbon solvent, such as toluene or xylene, or an aliphatichydrocarbon solvent, such as pentane, hexane, octane or decane.

Two or more of these solvents may be mixed together before use.Alternatively, each of the solvents may be used in a mixture with asolvent other than those mentioned above and/or water within aproportion not detrimental to full exertion of performance. The watercontent of the whole developer is preferably below 10 mass %. Morepreferably, the developer contains substantially no water. Namely, it ispreferred for the developer to consist substantially only of an organicsolvent. Even if so, the developer can contain any of surfactants to bedescribed hereinafter. Also, even if so, the developer may containunavoidable impurities from the atmosphere.

The amount of organic solvent used in the developer is preferably in therange of 80 to 100 mass %, more preferably 90 to 100 mass % and furthermore preferably 95 to 100 mass % based on the whole amount of thedeveloper.

It is especially preferred for the organic solvent contained in thedeveloper to be at least one member selected from among a ketonesolvent, an ester solvent, an alcohol solvent, an amide solvent and anether solvent.

The vapor pressure of the developer containing an organic solvent at 20°C. is preferably 5 kPa or below, more preferably 3 kPa or below and mostpreferably 2 kPa or below. When the vapor pressure of the developer is 5kPa or below, the evaporation of the developer on the substrate or in adevelopment cup can be suppressed so that the temperature uniformitywithin the plane of the wafer can be enhanced to thereby improve thedimensional uniformity within the plane of the wafer.

As particular examples of the developers exhibiting a vapor pressure of5 kPa or below, there can be mentioned a ketone solvent, such as1-octanone, 2-octanone, 1-nonanone, 2-nonanone, 4-heptanone, 2-hexanone,diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone ormethyl isobutyl ketone; an ester solvent, such as butyl acetate, amylacetate, propylene glycol monomethyl ether acetate, ethylene glycolmonoethyl ether acetate, diethylene glycol monobutyl ether acetate,diethylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate,3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl formate,propyl formate, ethyl lactate, butyl lactate or propyl lactate; analcohol solvent, such as n-propyl alcohol, isopropyl alcohol, n-butylalcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol,n-hexyl alcohol, 4-methyl-2-pentanol, n-heptyl alcohol, n-octyl alcoholor n-decanol; a glycol solvent, such as ethylene glycol, diethyleneglycol or triethylene glycol; a glycol ether solvent, such as ethyleneglycol monomethyl ether, propylene glycol monomethyl ether, ethyleneglycol monoethyl ether, propylene glycol monoethyl ether, diethyleneglycol monomethyl ether, triethylene glycol monoethyl ether ormethoxymethylbutanol; an ether solvent, such as tetrahydrofuran; anamide solvent, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide orN,N-dimethylformamide; an aromatic hydrocarbon solvent, such as tolueneor xylene, and an aliphatic hydrocarbon solvent, such as octane ordecane.

As particular examples of the developers exhibiting a vapor pressure of2 kPa or below, there can be mentioned a ketone solvent, such as1-octanone, 2-octanone, 1-nonanone, 2-nonanone, 4-heptanone, 2-hexanone,diisobutyl ketone, cyclohexanone, methylcyclohexanone or phenylacetone;an ester solvent, such as butyl acetate, amyl acetate, propylene glycolmonomethyl ether acetate, ethylene glycol monoethyl ether acetate,diethylene glycol monobutyl ether acetate, diethylene glycol monoethylether acetate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, ethyl lactate, butyl lactate or propyllactate; an alcohol solvent, such as n-butyl alcohol, sec-butyl alcohol,tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol,4-methyl-2-pentanol, n-heptyl alcohol, n-octyl alcohol or n-decanol; aglycol solvent, such as ethylene glycol, diethylene glycol ortriethylene glycol; a glycol ether solvent, such as ethylene glycolmonomethyl ether, propylene glycol monomethyl ether, ethylene glycolmonoethyl ether, propylene glycol monoethyl ether, diethylene glycolmonomethyl ether, triethylene glycol monoethyl ether ormethoxymethylbutanol; an amide solvent, such as N-methyl-2-pyrrolidone,N,N-dimethylacetamide or N,N-dimethylformamide; an aromatic hydrocarbonsolvent, such as xylene, and an aliphatic hydrocarbon solvent, such asoctane or decane.

According to necessity, an appropriate amount of surfactant can be addedto the developer.

The surfactant is not particularly limited. For example, use can be madeof any of ionic and nonionic fluorinated and/or siliconized surfactants.As such fluorinated and/or siliconized surfactants, there can bementioned, for example, those described in JP-A's S62-36663, S61-226746,S61-226745, S62-170950, 563-34540, H7-230165, H8-62834, H9-54432 andH9-5988 and U.S. Pat. Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330,5,436,098, 5,576,143, 5,294,511 and 5,824,451. Nonionic surfactants arepreferred. Using a nonionic fluorinated surfactant or siliconizedsurfactant is more preferred.

The amount of surfactant used is generally in the range of 0.001 to 5mass %, preferably 0.005 to 2 mass % and further more preferably 0.01 to0.5 mass % based on the whole amount of the developer.

The method of forming a pattern according to the present invention mayfurther comprise (d) rinsing the developed film by means of a rinseliquid containing a second organic solvent. It is preferred for therinse liquid to be one in which the density of particles each having adiameter of 0.3 μm or greater is 30 particles/ml or less. The particledensity is more preferably 25 particles/ml or less, further morepreferably 20 particles/ml or less, still further more preferably 15particles/ml or less, yet still further more preferably 10 particles/mlor less and most preferably 5 particles/ml or less.

As the means for regulating the particle density of the rinse liquidcontaining an organic solvent so as to fall within the above ranges,there can be mentioned, for example, the same methods as described abovein connection with the developer.

The rinse liquid for use in the rinse operation is not particularlylimited as long as it does not dissolve substantially the pattern afterdevelopment, and solutions containing common organic solvents can beused.

As the rinse liquid, there can be mentioned, for example, one containingat least one organic solvent selected from among a hydrocarbon solvent,a ketone solvent, an ester solvent, an alcohol solvent, an amide solventand an ether solvent. It is preferred for the rinse liquid to be onecontaining at least one organic solvent selected from among a ketonesolvent, an ester solvent, an alcohol solvent and an amide solvent. Arinse liquid containing an alcohol solvent or an ester solvent is morepreferred.

The rinse liquid further more preferably contains a monohydric alcohol,most preferably a monohydric alcohol having 5 or more carbon atoms.

The monohydric alcohol may be in the form of a linear chain, a branchedchain or a ring. Particular examples of the monohydric alcohols include1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol,1-pentanol, 2-pentanol, 1-hexanol, 4-methyl-2-pentanol, 1-heptanol,1-octanol, 2-hexanol, cyclopentanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol and 4-octanol. Particular examples of themonohydric alcohols each having 5 or more carbon atoms include1-hexanol, 2-hexanol, 4-methyl-2-pentanol, 1-pentanol and3-methyl-1-butanol.

Two or more of these components may be mixed together before use. Also,they may be mixed with other organic solvents before use.

The water content of the rinse liquid is preferably below 10 mass %,more preferably below 5 mass % and further more preferably below 3 mass%. Namely, the amount of organic solvent used in the rinse liquid ispreferably in the range of 90 to 100 mass %, more preferably 95 to 100mass % and most preferably 97 to 100 mass % based on the whole amount ofthe rinse liquid. Favorable development performance can be attained bycontrolling the water content of the rinse liquid at below 10 mass %.

The vapor pressure of the rinse liquid at 20° C. is preferably in therange of 0.05 to 5 kPa, more preferably 0.1 to 5 kPa and further morepreferably 0.12 to 3 kPa. When the vapor pressure of the rinse liquid isin the range of 0.05 to 5 kPa, not only can the temperature uniformitywithin the plane of the wafer be enhanced but also the swell attributedto the penetration of the rinse liquid can be suppressed to therebyimprove the dimensional uniformity within the plane of the wafer.

An appropriate amount of surfactant may be added to the rinse liquid.

[2] Method of Forming Pattern

The method of forming a pattern according to the present inventioncomprises:

-   -   (a) forming a chemically amplified resist composition into a        film,    -   (b) exposing the film to light, and    -   (c) developing the exposed film with the above-described        developer.

As mentioned above, this method may further comprise (d) rinsing thedeveloped film with a rinse liquid containing an organic solvent.

Preferably, this method still further comprises (e) baking the filmhaving been rinsed with the above rinse liquid. Namely, it is preferredfor the method of forming a pattern according to the present inventionto still further comprise the operation of postbake.

The method of forming a pattern according to the present inventionpreferably comprises the operation of baking (f) to be performed afterthe operation of film formation (a) but prior to the operation ofexposure (b).

Further, the method of forming a pattern according to the presentinvention preferably comprises the operation of baking (g) to beperformed after the operation of exposure (b) but prior to the operationof development (c).

Still further, the method of forming a pattern according to the presentinvention may comprise (h) the operation of development using an aqueousalkali developer.

Operation of Forming Resist Film

The resist film formed in the method of forming a pattern according tothe present invention is one formed from the chemically amplified resistcomposition according to the present invention to be describedhereinafter. In particular, the resist film is preferably formed on asubstrate.

The substrate that can be employed in the present invention is notparticularly limited. Use can be made of any of an inorganic substrateof silicon, SiN, SiO₂, TiN or the like, a coated inorganic substratesuch as SOG and substrates commonly employed in a semiconductorproduction process for an IC or the like, a circuit board productionprocess for a liquid crystal, a thermal head or the like and otherphotoapplication lithography processes. Further, according to necessity,an organic antireflection film may be provided between the film and thesubstrate.

In the method of forming a pattern according to the present invention,any of the above-mentioned operations can be carried out using generallyknown techniques.

Prebake Operation and Post-Exposure Bake Operation

As mentioned above, the method preferably comprises a prebake (PB)operation to be performed after the film formation but prior to theexposure operation.

Also, the method preferably comprises a post-exposure bake (PEB)operation to be performed after the exposure operation but prior to thedevelopment operation.

In both the PB operation and the PEB operation, the baking is preferablyperformed at 70 to 120° C., more preferably 80 to 110° C.

The baking time is preferably in the range of 30 to 300 seconds, morepreferably 30 to 180 seconds and further more preferably 30 to 90seconds.

The baking can be performed by means provided in the commonexposure/development equipment. The baking can also be performed using ahot plate or the like.

The baking accelerates the reaction in exposed areas, so that thesensitivity and pattern profile can be enhanced.

Operation of Exposure

In the present invention, the wavelength of the light source for use inthe exposure equipment is not limited. For example, a KrF excimer laserwavelength (248 nm), an ArF excimer laser wavelength (193 nm) and an F₂excimer laser wavelength (157 nm) can be applied.

With respect to the resist film according to the present invention, inthe stage of exposure to actinic rays or radiation, the exposure (liquidimmersion exposure) may be carried out while filling the space betweenthe film and the lens with a liquid (immersion medium) having arefractive index higher than that of air. This enhances the resolution.As the immersion medium, any liquid can be used as long as it exhibits arefractive index higher than that of air. Preferably, pure water isemployed.

In the liquid immersion exposure, the hydrophobic resin to be describedhereinafter may be added to the resist composition in advance.Alternatively, the formation of the resist film may be followed byproviding thereon a film that is highly insoluble in the immersionliquid (hereinafter also referred to as a “top coat”).

The performance expected from the top coat, the method of using thesame, etc. are described in Chapter 7 of “Process and Material of LiquidImmersion Lithography” published by CMC Publishing Co., Ltd.

From the viewpoint of the transparency to a laser of 193 nm wavelength,it is preferred for the top coat to be formed of a polymer notabundantly containing an aromatic moiety. As such a polymer, there canbe mentioned, for example, a hydrocarbon polymer, an acrylic esterpolymer, polymethacrylic acid, polyacrylic acid, polyvinyl ether, asiliconized polymer, a fluoropolymer or the like. Any of theabove-mentioned hydrophobic resins (HR) can be appropriately used as thetop coat, and commercially available top coat materials can also beappropriately used.

When the top coat is detached after the exposure, use may be made of adeveloper. Alternatively, a separate peeling agent may be used. Thepeeling agent is preferably a solvent exhibiting less permeation intothe film. Detachability by a developer is preferred from the viewpointof simultaneously performing the detachment operation and the operationof film development processing.

Operation of Development

As the development method, use can be made of, for example, a method inwhich the substrate is dipped in a tank filled with a developer for agiven period of time (dip method), a method in which a developer ispuddled on the surface of the substrate by its surface tension andallowed to stand still for a given period of time to thereby effectdevelopment (puddle method), a method in which a developer is sprayedonto the surface of the substrate (spray method), or a method in which adeveloper is continuously discharged onto the substrate being rotated ata given speed while scanning a developer discharge nozzle at a givenspeed (dynamic dispense method).

In the above various development methods, when the operation ofdischarging a developer toward the resist film through a developmentnozzle of a development apparatus is included, the discharge pressure ofdischarged developer (flow rate per area of discharged developer) ispreferably 2 ml/s/mm² or below, more preferably 1.5 ml/s/mm² or belowand further more preferably 1 ml/s/mm² or below. There is no particularlower limit of the flow rate. However, from the viewpoint ofthrough-put, it is preferred for the flow rate to be 0.2 ml/s/mm² orhigher.

Pattern defects attributed to any resist residue after development canbe markedly reduced by regulating the discharge pressure of dischargeddeveloper so as to fall within the above range.

The detail of the mechanism thereof is not apparent. However, it ispresumed that regulating the discharge pressure so as to fall within theabove range would lower the pressure on the resist film exerted by thedeveloper, thereby inhibiting any inadvertent shaving or crumbling ofthe resist film and resist pattern.

The discharge pressure of developer (ml/s/mm²) refers to a value at theoutlet of the development nozzle of the development apparatus.

As the method of regulating the discharge pressure of the developer,there can be mentioned, for example, a method in which the dischargepressure is regulated by means of a pump or the like, a method in whichthe discharge pressure of the developer is changed through the pressureregulation by supply from a pressure tank, or the like.

In the development operation, when use is made of the developer in whichthe density of particles each having a diameter of 0.3 μm or greater is30 particles/ml or less, the defect density can be reduced even if thefollowing rinse operation is skipped. In that instance, not only can thetotal amount of solvent required for pattern formation be decreased butalso the time required for pattern formation can be shortened.

Operation of Rinse

In the rinse operation, the wafer having undergone the development isrinsed using the rinse liquid containing an organic solvent to bedescribed hereinafter. The method of rinse treatment is not particularlylimited. For example, use can be made of any of a method in which therinse liquid is continuously applied onto the substrate being rotated ata given speed (spin application method), a method in which the substrateis dipped in a tank filled with the rinse liquid for a given period oftime (dip method) and a method in which the rinse liquid is sprayed ontothe surface of the substrate (spray method). Preferably, the rinsetreatment is carried out according to the spin application method amongthe above methods, and thereafter the substrate is rotated at a rotatingspeed of 2000 to 4000 rpm to thereby remove the rinse liquid from thetop of the substrate. The duration of substrate rotation can be setwithin the range ensuring the attainment of the removal of the rinseliquid from the top of the substrate, depending on the rotating speed.The duration of substrate rotation is generally in the range of 10seconds to 3 minutes.

Operation of Postbake

Any inter-pattern and intra-pattern remaining developer and/or rinseliquid can be removed by carrying out a postbake. The postbake operationis generally performed at 40 to 160° C., preferably 70 to 95° C., for aperiod of 10 seconds to 3 minutes, preferably 30 to 90 seconds.

[3] Chemically Amplified Resist Composition

[3-1] Resin (A)

A negative pattern is formed from the chemically amplified resistcomposition according to the present invention by the above patternforming method of the present invention.

Namely, in the resist film obtained from the chemically amplified resistcomposition according to the present invention, the exposed areas havetheir solubility in the developer containing an organic solventdecreased under the action of an acid and are rendered insoluble orhighly insoluble therein. On the other hand, the nonexposed areas aresoluble in the developer containing an organic solvent. Thus, a negativepattern is obtained.

It is optional for the resin (A) to contain a repeating unit containingan acid group. Preferably, the resin (A) does not contain such arepeating unit.

As the acid group, there can be mentioned, for example, a carboxylgroup, a sulfonamido group, a sulfonylimido group, a bissulfonylimidogroup, an aliphatic alcohol substituted at its a-position with anelectron withdrawing group (for example, a hexafluoroisopropanol group—C(CF₃)₂OH) or the like.

When the resin (A) contains an acid group, the content of repeating unitcontaining an acid group in the resin (A) is preferably 10 mol % orbelow, more preferably 5 mol % or below. When the resin (A) contains arepeating unit containing an acid group, the content of repeating unitcontaining an acid group in the resin (A) is generally not lower than 1mol %.

As long as the film formed from the resist composition is soluble in thedeveloper containing an organic solvent, this resin does not necessarilyhave to be by itself soluble in the developer. For example, the resincan be by itself insoluble in the developer when the film formed fromthe resist composition is soluble in the developer, depending on theproperties and content of other components contained in the resistcomposition.

The resin (A) is generally synthesized by polymerization, such asradical polymerization, of monomers each with a polymerizable partialstructure. The resin (A) contains the repeating units derived from themonomers each with a polymerizable partial structure. As thepolymerizable partial structure, there can be mentioned, for example, anethylenically polymerizable partial structure.

The various repeating units that can be contained in the resin (A) willbe described in detail below.

-   -   (a1) Repeating unit containing an acid-decomposable group

The resin (A) is a resin whose solubility in the developer containing anorganic solvent is decreased by the action of an acid. The resin (A)comprises, in its principal chain or side chain, or both of itsprincipal chain and side chain, a repeating unit containing a group(hereinafter also referred to as “an acid-decomposable group”) that isdecomposed by the action of an acid to thereby produce a polar group.When the polar group is produced, the affinity of the resin for thedeveloper containing an organic solvent is lowered to thereby promotethe insolubilization or solubility drop (conversion to negative) of theresin.

It is preferred for the acid-decomposable group to have a structure inwhich the polar group is protected by a group that is decomposed by theaction of an acid to thereby be cleaved.

The polar group is not particularly limited as long as it is a groupinsolubilized in the developer containing an organic solvent. Aspreferred examples thereof, there can be mentioned acid groups (groupsthat are dissociated in a 2.38 mass % aqueous tetramethylammoniumhydroxide solution conventionally used as a resist developer), such as acarboxyl group, a fluoroalcohol group (preferably ahexafluoroisopropanol) and a sulfonic acid group.

The acid-decomposable group is preferably a group as obtained bysubstituting the hydrogen atom of any of these groups with anacid-cleavable group.

As the acid-cleavable group, there can be mentioned, for example,—C(R₃₆)(R₃₇)(R₃₈), —C(R₃₆)(R₃₇)(OR₃₉), —C(R₀₁)(R₀₂)(OR₃₉) or the like.

In the formulae, each of R₃₆ to R₃₉ independently represents an alkylgroup, a cycloalkyl group, an aryl group, an aralkyl group or an alkenylgroup. R₃₆ and R₃₇ may be bonded to each other to thereby form a ring.

Each of R₀₁ and R₀₂ independently represents a hydrogen atom, an alkylgroup, a cycloalkyl group, an aryl group, an aralkyl group or an alkenylgroup.

Preferably, the acid-decomposable group is a cumyl ester group, an enolester group, an acetal ester group, a tertiary alkyl ester group or thelike. A tertiary alkyl ester group is more preferred.

The repeating unit with an acid-decomposable group that may be containedin the resin (A) is preferably any of those of the following generalformula (AI).

In general formula (AI),

Xa₁ represents a hydrogen atom, an optionally substituted methyl groupor any of the groups of the formula —CH₂—R₉. R₉ represents a hydroxylgroup or a monovalent organic group. The monovalent organic group is,for example, an alkyl group having 5 or less carbon atoms or an acylgroup having 5 or less carbon atoms. Preferably, the monovalent organicgroup is an alkyl group having 3 or less carbon atoms, more preferably amethyl group. Xa₁ is preferably a hydrogen atom, a methyl group, atrifluoromethyl group or a hydroxymethyl group, more preferably ahydrogen atom, a methyl group or a hydroxymethyl group.

T represents a single bond or a bivalent connecting group.

Each of Rx₁ to Rx₃ independently represents an alkyl group (linear orbranched) or a cycloalkyl group (monocyclic or polycyclic).

Rx₂ and Rx₃ may be bonded with each other to thereby form a cycloalkylgroup (monocyclic or polycyclic).

As the bivalent connecting group represented by T, there can bementioned an alkylene group, a group of the formula —COO-Rt-, a group ofthe formula —O-Rt-, a group comprising a combination of at least two ofthese, or the like. The total number of carbon atoms in the bivalentconnecting group is preferably in the range of 1 to 12. In the formulae,Rt represents an alkylene group or a cycloalkylene group.

T is preferably a single bond or a group of the formula —COO-Rt-Rt ispreferably an alkylene group having 1 to 5 carbon atoms, more preferablya —CH₂-group, —(CH₂)₂— group or —(CH₂)₃— group.

The alkyl group represented by each of Rx₁ to Rx₃ is preferably onehaving 1 to 4 carbon atoms, such as a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, an isobutyl groupor a t-butyl group.

The cycloalkyl group represented by each of Rx₁ to Rx₃ is preferably acycloalkyl group of one ring, such as a cyclopentyl group or acyclohexyl group, or a cycloalkyl group of multiple rings, such as anorbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl groupor an adamantyl group.

The cycloalkyl group formed by bonding of Rx₂ and Rx₃ is preferably acycloalkyl group of one ring, such as a cyclopentyl group or acyclohexyl group, or a cycloalkyl group of multiple rings, such as anorbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl groupor an adamantyl group. The cycloalkyl group of a single ring having 5 or6 carbon atoms is particularly preferred.

In a preferred mode, Rx₁ is a methyl group or an ethyl group, and Rx₂and Rx₃ are bonded with each other to thereby form any of theabove-mentioned cycloalkyl groups.

Each of the groups, above, may have a substituent. As the substituent,there can be mentioned, for example, an alkyl group (having 1 to 4carbon atoms), a cycloalkyl group (having 3 to 15 carbon atoms), ahalogen atom, a hydroxyl group, an alkoxy group (having 1 to 4 carbonatoms), a carboxyl group, an alkoxycarbonyl group (having 2 to 6 carbonatoms) or the like. Substituents having 8 or less carbon atoms arepreferred.

Specific examples of the preferred repeating units withacid-decomposable groups will be shown below, which however in no waylimit the scope of the present invention.

In the following formulae, each of Rx and Xa₁ represents a hydrogenatom, CH₃, CF₃ or CH₂OH. Each of Rxa and Rxb represents an alkyl grouphaving 1 to 4 carbon atoms. Z, each independently in the presence of twoor more groups, represents a substituent containing a polar group. prepresents 0 or a positive integer. As the substituent containing apolar group, there can be mentioned, for example, a linear or branchedalkyl group, or cycloalkyl group, in which a hydroxyl group, a cyanogroup, an amino group, an alkylamido group or a sulfonamido group isintroduced. An alkyl group in which a hydroxyl group is introduced ispreferred. As a branched alkyl group, an isopropyl group is especiallypreferred.

When the resin (A) comprises a plurality of repeating units eachcontaining an acid-decomposable group, or when a plurality of resins (A)comprise repeating units containing acid-decomposable groups differentfrom each other, as preferred combinations of repeating units, there canbe mentioned, for example, the following. In the formulae shown below,each of R's independently represents a hydrogen atom or a methyl group.

As forms of repeating units other than those shown above by way ofexample, preferred use is made of the following repeating units thatwhen acted on by an acid, each produce an alcoholic hydroxyl group. Theterm “alcoholic hydroxyl group” used herein means a nonphenolic hydroxylgroup, in particular, a hydroxyl group whose pKa value is in the rangeof 12 to 20.

(a2) Repeating Unit Containing an Alcoholic Hydroxyl Group

The resin (A) may comprise, in at least either the principal chain or aside chain thereof, a repeating unit (a2) containing an alcoholichydroxyl group. An enhancement of the adherence to a substrate can beexpected by virtue of the introduction of such a repeating unit. Whenthe resist composition of the present invention contains a crosslinkingagent to be described hereinafter, it is preferred for the resin (A) tocomprise the repeating unit (a2) containing an alcoholic hydroxyl group.This is because as the alcoholic hydroxyl group functions as acrosslinking group, the hydroxyl group reacts with a crosslinking agentunder the action of an acid to thereby promote the insolubilization orsolubility drop of the resist film in a developer containing an organicsolvent with the result that the effect of enhancing the line widthroughness (LWR) performance is exerted.

In the present invention, the alcoholic hydroxyl group is not limited aslong as it is a hydroxyl group bonded to a hydrocarbon group and isother than a hydroxyl group (phenolic hydroxyl group) directly bondedonto an aromatic ring. However, in the present invention, it ispreferred for the alcoholic hydroxyl group to be other than the hydroxylgroup of an aliphatic alcohol substituted at its α-position with anelectron withdrawing group, mentioned hereinbefore as an acid group.From the viewpoint of enhancing the efficiency of the reaction with acrosslinking agent (C), it is preferred for the alcoholic hydroxyl groupto be a primary alcoholic hydroxyl group (group in which the carbon atomsubstituted with a hydroxyl group has two hydrogen atoms besides thehydroxyl group) or a secondary alcoholic hydroxyl group in which anotherelectron withdrawing group is not bonded to the carbon atom substitutedwith a hydroxyl group.

Preferably 1 to 3 alcoholic hydroxyl groups, more preferably 1 or 2alcoholic hydroxyl groups are introduced in each repeating unit (a2).

As these repeating units, there can be mentioned the repeating units ofgeneral formulae (2) and (3).

In general formula (2) above, at least either Rx or R represents astructure with an alcoholic hydroxyl group.

In general formula (3), at least any of two Rx's and R represents astructure with an alcoholic hydroxyl group. Two Rx's may be identical toor different from each other.

As the structure with an alcoholic hydroxyl group, there can bementioned, for example, a hydroxyalkyl group (preferably 2 to 8 carbonatoms, more preferably 2 to 4 carbon atoms), a hydroxycycloalkyl group(preferably 4 to 14 carbon atoms), a cycloalkyl group substituted with ahydroxyalkyl group (preferably 5 to 20 carbon atoms in total), an alkylgroup substituted with a hydroxyalkoxy group (preferably 3 to 15 carbonatoms in total), a cycloalkyl group substituted with a hydroxyalkoxygroup (preferably 5 to 20 carbon atoms in total) or the like. Asmentioned above, a residue of primary alcohol is preferred. Thestructure —(CH₂)n-OH (n is an integer of 1 or greater, preferably aninteger of 2 to 4) is more preferred.

Rx represents a hydrogen atom, a halogen atom, a hydroxyl group, anoptionally substituted alkyl group (preferably 1 to 4 carbon atoms) oran optionally substituted cycloalkyl group (preferably 5 to 12 carbonatoms). As preferred substituents that may be introduced in the alkylgroup and cycloalkyl group represented by Rx, there can be mentioned ahydroxyl group and a halogen atom. As the halogen atom represented byRx, there can be mentioned a fluorine atom, a chlorine atom, a bromineatom or an iodine atom. Rx is preferably a hydrogen atom, a methylgroup, a hydroxymethyl group, a hydroxyl group or a trifluoromethylgroup. A hydrogen atom and a methyl group are especially preferred.

R represents an optionally hydroxylated hydrocarbon group. Thehydrocarbon group represented by R is preferably a saturated hydrocarbongroup. As such, there can be mentioned an alkyl group (preferably 1 to 8carbon atoms, more preferably 2 to 4 carbon atoms) or a mono- orpolycyclohydrocarbon group (preferably 3 to 20 carbon atoms, forexample, an alicyclic group to be described hereinafter). In theformula, n′ is an integer of 0 to 2.

The repeating unit (a2) is preferably a repeating unit derived from anester of acrylic acid in which the principal chain at its α-position(for example, Rx in formula (2)) may be substituted, more preferably arepeating unit derived from a monomer with a structure corresponding toformula (2). Further, containing an alicyclic group in the unit ispreferred. With respect to the alicyclic group, a mono- or polycyclicstructure can be considered. A polycyclic structure is preferred fromthe viewpoint of the resistance to etching.

As the alicyclic groups, there can be mentioned, for example, monocyclicstructures, such as cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl andcyclooctyl, and polycyclic structures, such as norbornyl, isobornyl,tricyclodecanyl, tetracyclododecanyl, hexacycloheptadecanyl, adamantyl,diadamantyl, spirodecanyl and spiroundecanyl. Of these, adamantyl,diadamantyl and norbornyl structures are preferred.

Examples of the repeating units (a2) are shown below, which however inno way limit the scope of the present invention. In the examples, Rxrepresents a hydrogen atom or a methyl group.

The repeating unit (a2) may have a structure in which at least one ofthe above-mentioned repeating unit (a1) and repeating units (a3) and(a4) to be described hereinafter contains an alcoholic hydroxyl group.For example, the repeating unit (a2) may have a structure in which inthe above-mentioned repeating unit (a1) containing an acid-decomposablegroup, the moiety cleaved under the action of an acid contains analcoholic hydroxyl group. It is presumed that the efficiency ofcrosslinking can be optimized by containing such a repeating unit. Asthis structure, there can be mentioned, for example, a structure inwhich in the above general formula (A1), the moiety of atomic group—C(Rx₁)(Rx₂)(Rx₃) contains a hydroxyl group. More particularly, therecan be mentioned, for example, the structures of the repeating units ofgeneral formula (AI) in which the moiety of atomic group—C(Rx₁)(Rx₂)(Rx₃) is expressed by the formula below wherein R representsa hydroxyl group, a hydroxylated linear or branched alkyl group or ahydroxylated cycloalkyl group and p is an integer of 1 or greater.

(a3) Repeating Unit Containing a Nonpolar Group

It is preferred for the resin (A) to further comprise a repeating unit(a3) containing a nonpolar group. By introducing this repeating unit,not only can leaching of low-molecular components from the resist filminto an immersion liquid in the stage of liquid-immersion exposure bereduced but also the solubility of the resin in the stage of developmentwith a developer containing an organic solvent can be appropriatelyregulated. It is preferred for the repeating unit (a3) containing anonpolar group to be a repeating unit in which no polar group (forexample, the above-mentioned acid group, a hydroxyl group, a cyano groupor the like) is contained. It is also preferred for the repeating unit(a3) to be a repeating unit containing neither the acid-decomposablegroup mentioned above nor the lactone structure to be describedhereinafter. As these repeating units, there can be mentioned therepeating units of general formulae (4) and (5) below.

In the general formulae,

R₅ represents a hydrocarbon group having neither a hydroxyl group nor acyano group.

Ra, or each of Ra's independently, represents a hydrogen atom, ahydroxyl group, a halogen atom or an alkyl group (preferably 1 to 4carbon atoms). A substituent may be introduced in the alkyl grouprepresented by Ra, and as the substituent, there can be mentioned ahydroxyl group or a halogen atom. As the halogen atom represented by Ra,there can be mentioned a fluorine atom, a chlorine atom, a bromine atomor an iodine atom. Ra is preferably a hydrogen atom, a methyl group, atrifluoromethyl group or a hydroxymethyl group. A hydrogen atom and amethyl group are most preferred.

In the formula, n is an integer of 0 to 2.

It is preferred for R₅ to have at least one cyclic structure.

The hydrocarbon groups represented by R₅ include, for example, linearand branched hydrocarbon groups, monocyclohydrocarbon groups andpolycyclohydrocarbon groups. From the viewpoint of the resistance to dryetching, it is preferred for R₅ to include monocyclohydrocarbon groupsand polycyclohydrocarbon groups, especially polycyclohydrocarbon groups.

R₅ preferably represents any of the groups of formula: -L₄-A₄-(R₄) L₄represents a single bond or a bivalent hydrocarbon group, beingpreferably a single bond, an alkylene group (preferably 1 to 3 carbonatoms) or a cycloalkylene group (preferably 5 to 7 carbon atoms). Morepreferably, L₄ represents a single bond. A₄ represents a (n4+1)-valenthydrocarbon group (preferably 3 to 30 carbon atoms, more preferably 3 to14 carbon atoms and further more preferably 6 to 12 carbon atoms),preferably an alicyclic hydrocarbon group of a single ring or multiplerings. In the formula, n4 is an integer of 0 to 5, preferably an integerof 0 to 3. R₄ represents a hydrocarbon group, being preferably an alkylgroup (preferably 1 to 3 carbon atoms) or a cycloalkyl group (preferably5 to 7 carbon atoms).

As the linear or branched hydrocarbon group, there can be mentioned, forexample, an alkyl group having 3 to 12 carbon atoms. As the monocyclichydrocarbon group, there can be mentioned, for example, a cycloalkylgroup having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12carbon atoms or a phenyl group. Preferably, the monocyclic hydrocarbongroup is a monocyclic saturated hydrocarbon group having 3 to 7 carbonatoms.

The polycyclic hydrocarbon groups include ring-assembly hydrocarbongroups (for example, a bicyclohexyl group) and crosslinked-ringhydrocarbon groups. As the crosslinked-ring hydrocarbon groups, therecan be mentioned, for example, a bicyclic hydrocarbon group, a tricyclichydrocarbon group and a tetracyclic hydrocarbon group. Further, thecrosslinked-ring hydrocarbon groups include condensed-ring hydrocarbongroups (for example, groups each resulting from condensation of aplurality of 5- to 8-membered cycloalkane rings). As preferredcrosslinked-ring hydrocarbon groups, there can be mentioned a norbornylgroup and an adamantyl group.

A substituent may further be introduced in each of these groups. As apreferred substituent, there can be mentioned a halogen atom, an alkylgroup or the like. As a preferred halogen atom, there can be mentioned abromine atom, a chlorine atom or a fluorine atom. As a preferred alkylgroup, there can be mentioned a methyl, an ethyl, a butyl or a t-butylgroup. Still further, a substituent may be introduced in this alkylgroup. As the substituent that may still further be introduced, therecan be mentioned a halogen atom or an alkyl group.

Particular examples of the repeating units each containing a nonpolargroup are shown below, which in no way limit the scope of the presentinvention. In the formulae, Ra represents a hydrogen atom, a hydroxylgroup, a halogen atom or an optionally substituted alkyl group having 1to 4 carbon atoms. As preferred substituents that may be introduced inthe alkyl group represented by Ra, there can be mentioned a hydroxylgroup and a halogen atom. As the halogen atom represented by Ra, therecan be mentioned a fluorine atom, a chlorine atom, a bromine atom or aniodine atom. Ra is preferably a hydrogen atom, a methyl group, ahydroxymethyl group or a trifluoromethyl group. A hydrogen atom and amethyl group are especially preferred.

(a4) Repeating Unit Containing a Lactone Structure

The resin (A) may have a repeating unit containing a lactone structure.

Any lactone groups can be employed as long as a lactone structure ispossessed therein. However, lactone structures of a 5 to 7-membered ringare preferred, and in particular, those resulting from condensation oflactone structures of a 5 to 7-membered ring with other cyclicstructures effected in a fashion to form a bicyclo structure or spirostructure are preferred. The possession of repeating units having alactone structure represented by any of the following general formulae(LC1-1) to (LC1-17) is more preferred. The lactone structures may bedirectly bonded to the principal chain of the resin. Preferred lactonestructures are those of formulae (LC1-1), (LC1-4), (LC1-5), (LC1-6),(LC1-13), (LC1-14) and (LC1-17). The use of these specified lactonestructures would ensure improvement in the LWR and development defect.

The presence of a substituent (Rb₂) on the portion of the lactonestructure is optional. As a preferred substituent (Rb₂), there can bementioned an alkyl group having 1 to 8 carbon atoms, a cycloalkyl grouphaving 4 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms,an alkoxycarbonyl group having 1 to 8 carbon atoms, a carboxyl group, ahalogen atom, a hydroxyl group, a cyano group, an acid-decomposablegroup or the like. Of these, an alkyl group having 1 to 4 carbon atoms,a cyano group and an acid-decomposable group are more preferred. In theformulae, n₂ is an integer of 0 to 4. When n₂ is 2 or greater, theplurality of present substituents (Rb₂) may be identical to or differentfrom each other. Further, the plurality of present substituents (Rb₂)may be bonded to each other to thereby form a ring.

The repeating unit having a lactone group is generally present in theform of optical isomers. Any of the optical isomers may be used. It isboth appropriate to use a single type of optical isomer alone and to usea plurality of optical isomers in the form of a mixture. When a singletype of optical isomer is mainly used, the optical purity (ee) thereofis preferably 90% or higher, more preferably 95% or higher.

As the repeating unit having a lactone structure, it is preferred forthe resin (A) to contain any of the repeating units represented bygeneral formula (III) below.

In formula (III),

A represents an ester bond (—COO—) or an amido bond (—CONH—).

Ro, each independently in the presence of two or more groups, representsan alkylene group, a cycloalkylene group or a combination thereof.

Z, each independently in the presence of two or more groups, representsan ether bond, an ester bond, an amido bond, a urethane bond

or a urea bond

Each of Rs independently represents a hydrogen atom, an alkyl group,cycloalkyl group or an aryl group.

R₈ represents a monovalent organic group with a lactone structure.

n represents the number of repetitions of the structure of the formula—R₀—Z— and is an integer of 0 to 5. n preferably represents 0 or 1.

R₇ represents a hydrogen atom, a halogen atom or an optionallysubstituted alkyl group.

Each of the alkylene group and cycloalkylene group represented by R₀ mayhave a substituent.

Z preferably represents an ether bond or an ester bond, most preferablyan ester bond.

The alkyl group represented by R₇ is preferably an alkyl group having 1to 4 carbon atoms, more preferably a methyl group or an ethyl group andmost preferably a methyl group. As the substituent of the alkyl group,there can be mentioned, for example, a hydroxyl group, a halogen atomand the like.

Each of the alkylene group and cycloalkylene group represented by R₀ andthe alkylene group represented by R₇ may have a substituent. As thesubstituent, there can be mentioned, for example, a halogen atom such asa fluorine atom, a chlorine atom or a bromine atom, a mercapto group, ahydroxyl group, an alkoxy group such as a methoxy group, an ethoxygroup, an isopropoxy group, a t-butoxy group or a benzyloxy group, anacyloxy group such as an acetyloxy group or a propionyloxy group and thelike.

R₇ preferably represents a hydrogen atom, a methyl group, atrifluoromethyl group or a hydroxymethyl group.

The alkylene group represented by R₀ is preferably a chain alkylenegroup having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms,for example, a methylene group, an ethylene group, a propylene group orthe like. The cycloalkylene group is preferably a cycloalkylene grouphaving 3 to 20 carbon atoms. As such, there can be mentioned, forexample, cyclohexylene, cyclopentylene, norbornylene, adamantylene orthe like. The chain alkylene groups are preferred from the viewpoint ofthe exertion of the effect of the present invention. A methylene groupis most preferred.

The monovalent organic group with a lactone structure represented by R₈is not limited as long as the lactone structure is contained. Asparticular examples thereof, there can be mentioned the lactonestructures of the above general formulae (LC1-1) to (LC1-17). Of these,the structures of general formula (LC1-4) are most preferred. In generalformulae (LC1-1) to (LC1-17), n₂ is more preferably 2 or less.

R₈ preferably represents a monovalent organic group with anunsubstituted lactone structure or a monovalent organic group with alactone structure substituted with a methyl group, a cyano group or analkoxycarbonyl group. More preferably, R₈ represents a monovalentorganic group with a lactone structure substituted with a cyano group(cyanolactone).

Specific examples of the repeating units having a lactone structure willbe shown below, which however in no way limit the scope of the presentinvention.

In the following specific examples, Rx represents H, CH₃, CH₂OH or CF₃.

The repeating units having an especially preferred lactone structurewill be shown below. An improvement in pattern profile and iso-densebias can be attained by selection of the most appropriate lactonestructure.

In the following formulae, Rx represents H, CH₃, CH₂OH or CF₃.

In the following specific examples, R represents a hydrogen atom, anoptionally substituted alkyl group or a halogen atom. Preferably, Rrepresents a hydrogen atom, a methyl group, a hydroxymethyl group or atrifluoromethyl group.

Two or more types of lactone repeating units can be simultaneouslyemployed in order to enhance the effects of the present invention.

Resin (A) may have, in addition to the foregoing repeating structuralunits, various repeating structural units for the purpose of regulatingthe dry etching resistance, standard developer adaptability, substrateadhesion, resist profile and generally required properties of the resistsuch as resolving power, heat resistance and sensitivity.

Resin (A) may be a resin composed of a mixture of two or more differentresins. For example, a resin composed of a mixture of a resin comprisinga repeating unit (a2) and a resin comprising a repeating unit (a3) canbe used in order to regulate the dry etching resistance, standarddeveloper adaptability, adherence to substrates, resist profile andgenerally required properties for the resist, such as resolving power,heat resistance, sensitivity and the like.

Also, preferred use is made of a resin composed of a mixture of a resincomprising a repeating unit (a1) and a resin in which no repeating unit(a1) is contained.

When the composition of the present invention is used in ArF exposure,it is preferred for the resin (A) contained in the composition of thepresent invention to contain substantially no aromatic group (inparticular, the ratio of the repeating unit containing an aromatic groupin the resin is preferably up to 5 mol %, more preferably up to 3 mol %and ideally 0 mol %, namely containing no aromatic group) from theviewpoint of transparency to ArF light. It is preferred for the resin(A) to have an alicyclic hydrocarbon structure of a single ring ormultiple rings.

Further, it is preferred for the resin (A) to contain neither a fluorineatom nor a silicon atom from the viewpoint of the compatibility withhydrophobic resins to be described hereinafter.

In the present invention, the contents of individual repeating units areas follows. A plurality of different repeating units may be contained.When a plurality of different repeating units are contained, thefollowing content refers to the total amount thereof.

The content of repeating unit (a1) containing an acid-decomposablegroup, based on all the repeating units constructing the resin (A), ispreferably in the range of 20 to 70 mol %, more preferably 30 to 60 mol%.

When the resin (A) contains a repeating unit (a2) containing analcoholic hydroxyl group, the content thereof based on all the repeatingunits constructing the resin (A) is generally in the range of 10 to 80mol %, preferably 10 to 60 mol %.

When the resin (A) contains a repeating unit (a3) containing a nonpolargroup, the content thereof based on all the repeating units constructingthe resin (A) is generally in the range of 20 to 80 mol %, preferably 30to 60 mol %.

When the resin (A) contains a repeating unit (a4) containing a lactone,the content thereof based on all the repeating units of the resin (A) ispreferably in the range of 15 to 60 mol %, more preferably 20 to 50 mol% and further more preferably 30 to 50 mol %.

The molar ratio of individual repeating units contained in the resin (A)can be appropriately set for regulating the resist resistance to dryetching, developer adaptability, adherence to substrates, resistprofile, generally required properties for resists, such as resolvingpower, heat resistance and sensitivity, and the like.

Resin (A) can be synthesized by conventional techniques (for example,radical polymerization). As general synthetic methods, there can bementioned, for example, a batch polymerization method in which a monomerspecies and an initiator are dissolved in a solvent and heated so as toaccomplish polymerization and a dropping polymerization method in whicha solution of monomer species and initiator is added by dropping to aheated solvent over a period of 1 to 10 hours. The droppingpolymerization method is preferred. As for detailedsynthesis/purification methods, reference can be made to the methodsdescribed above with respect to the main resins of the resist, thedescription of Chapter 2 “Polymer Synthesis” of “5-th EditionExperimental Chemistry Course 26 Polymer Chemistry” issued by MaruzenCo., Ltd., etc.

The weight average molecular weight of resin (A) in terms of polystyrenemolecular weight as measured by GPC is preferably in the range of 1000to 200,000, more preferably 2000 to 20,000, still more preferably 3000to 15,000 and further preferably 5000 to 13,000. The regulation of theweight average molecular weight to 1000 to 200,000 would preventdeteriorations of heat resistance and dry etching resistance and alsoprevent deterioration of developability and increase of viscosityleading to poor film forming property.

Use is made of the resin whose dispersity (molecular weightdistribution) is generally in the range of 1 to 3, preferably 1 to 2.6,more preferably 1 to 2 and most preferably 1.4 to 1.7. The lower themolecular weight distribution, the more excellent the resolving powerand resist profile and the smoother the side wall of the resist patternto thereby attain an excellence in roughness.

In the present invention, the content ratio of resin (A) based on thetotal solid content of the whole composition is preferably in the rangeof 65 to 97 mass %, more preferably 75 to 95 mass %.

In the present invention, the resins (A) may be used either individuallyor in combination.

[3-2] Compound (B) that when Exposed to Actinic Rays or Radiation,Generates an Acid.

The composition of the present invention contains a compound that whenexposed to actinic rays or radiation, generates an acid (hereinafterreferred to as an “acid generator”).

As the acid generator, use can be made of a member appropriatelyselected from among a photoinitiator for photocationic polymerization, aphotoinitiator for photoradical polymerization, a photo-achromatic agentand photo-discoloring agent for dyes, any of generally known compoundsthat when exposed to actinic rays or radiation, generate an acid,employed in microresists, etc., and mixtures thereof.

For example, as the acid generator, there can be mentioned a diazoniumsalt, a phosphonium salt, a sulfonium salt, an iodonium salt, an imidesulfonate, an oxime sulfonate, diazosulfone, disulfone or o-nitrobenzylsulfonate.

As preferred compounds among the acid generators, there can be mentionedthose of general formulae (ZI), (ZII) and (ZIII), below.

In general formula (ZI), each of R₂₀₁, R₂₀₂ and R₂₀₃ independentlyrepresents an organic group. The number of carbon atoms of the organicgroup represented by R₂₀₁, R₂₀₂ and R₂₀₃ is generally in the range of 1to 30, preferably 1 to 20. Two of R₂₀₁ to R₂₀₃ may be bonded with eachother to thereby form a ring structure, and the ring within the same maycontain an oxygen atom, a sulfur atom, an ester bond, an amido bond or acarbonyl group. As the group formed by bonding of two of R₂₀₁ to R₂₀₃,there can be mentioned an alkylene group (for example, a butylene groupor a pentylene group). Z⁻ represents a normucleophilic anion.

As the normucleophilic anion represented by Z⁻, there can be mentioned,for example, a sulfonate anion, a carboxylate anion, a sulfonylimidoanion, a bis(alkylsulfonyl)imido anion, a tris(alkylsulfonyl)methideanion or the like.

The normucleophilic anion means an anion whose capability of inducing anucleophilic reaction is extremely low and is an anion capable ofinhibiting any temporal decomposition by intramolecular nucleophilicreaction. This would realize an enhancement of the temporal stability ofthe actinic-ray- or radiation-sensitive resin composition.

As the sulfonate anion, there can be mentioned, for example, analiphatic sulfonate anion, an aromatic sulfonate anion, a camphorsulfonate anion or the like.

As the carboxylate anion, there can be mentioned, for example, analiphatic carboxylate anion, an aromatic carboxylate anion, an aralkylcarboxylate anion or the like.

The aliphatic moiety of the aliphatic sulfonate anion may be an alkylgroup or a cycloalkyl group, being preferably an alkyl group having 1 to30 carbon atoms or a cycloalkyl group having 3 to 30 carbon atoms.

As a preferred aromatic group of the aromatic sulfonate anion, there canbe mentioned an aryl group having 6 to 14 carbon atoms, for example, aphenyl group, a tolyl group, a naphthyl group or the like.

The alkyl group, cycloalkyl group and aryl group of the aliphaticsulfonate anion and aromatic sulfonate anion may have a substituent.

Anions capable of producing arylsulfonic acids of formula (BI) below arepreferably used as the aromatic sulfonate anion.

In formula (BI),

Ar represents an aromatic ring, in which a substituent other than thesulfonic acid group and A-group may further be introduced.

In the formula, p is an integer of 0 or greater.

A represents a group comprising a hydrocarbon group.

When p is 2 or greater, a plurality of A-groups may be identical to ordifferent from each other.

Formula (BI) will be described in greater detail below.

The aromatic ring represented by Ar is preferably an aromatic ringhaving 6 to 30 carbon atoms.

In particular, the aromatic ring is preferably a benzene ring, anaphthalene ring or an anthracene ring. A benzene ring is morepreferred.

As the substituent other than the sulfonic acid group and A-group thatcan further be introduced in the aromatic ring, there can be mentioned ahalogen atom (a fluorine atom, a chlorine atom, a bromine atom, aniodine atom or the like), a hydroxyl group, a cyano group, a nitrogroup, a carboxyl group or the like. When two or more substituents areintroduced, at least two thereof may be bonded to each other to therebyform a ring.

As the hydrocarbon group of the group comprising a hydrocarbon grouprepresented by A, there can be mentioned a noncyclic hydrocarbon groupor a cycloaliphatic group. This hydrocarbon group preferably has 3 ormore carbon atoms.

With respect to the A-group, it is preferred for the carbon atomadjacent to Ar to be a tertiary or quaternary carbon atom.

As the noncyclic hydrocarbon group represented by A, there can bementioned an isopropyl group, a t-butyl group, a t-pentyl group, aneopentyl group, a s-butyl group, an isobutyl group, an isohexyl group,a 3,3-dimethylpentyl group, a 2-ethylhexyl group or the like. Withrespect to the upper limit of the number of carbon atoms of thenoncyclic hydrocarbon group, the number is preferably 12 or less, morepreferably 10 or less.

As the cycloaliphatic group represented by A, there can be mentioned acycloalkyl group such as a cyclobutyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group or a cyclooctyl group, anadamantyl group, a norbornyl group, a bornyl group, a camphenyl group, adecahydronaphthyl group, a tricyclodecanyl group, a tetracyclodecanylgroup, a camphoroyl group, a dicyclohexyl group, a pinenyl group or thelike. The cycloaliphatic group may have a substituent. With respect tothe upper limit of the number of carbon atoms of the cycloaliphaticgroup, the number is preferably 15 or less, more preferably 12 or less.

As a substituent that may be introduced in the noncyclic hydrocarbongroup or cycloaliphatic group, there can be mentioned, for example, ahalogen group such as a fluorine atom, a chlorine atom, a bromine atomor an iodine atom, an alkoxy group such as a methoxy group, an ethoxygroup or a tert-butoxy group, an aryloxy group such as a phenoxy groupor a p-tolyloxy group, an alkylthioxy group such as a methylthioxygroup, an ethylthioxy group or a tert-butylthioxy group, an arylthioxygroup such as a phenylthioxy group or a p-tolylthioxy group, analkoxycarbonyl group such as a methoxycarbonyl group or a butoxycarbonylgroup, a phenoxycarbonyl group, an acetoxy group, a linear or branchedalkyl group such as a methyl group, an ethyl group, a propyl group, abutyl group, a heptyl group, a hexyl group, a dodecyl group or a2-ethylhexyl group, a cycloalkyl group such as a cyclohexyl group, analkenyl group such as a vinyl group, a propenyl group or a hexenylgroup, an alkynyl group such as an acetylene group, a propynyl group ora hexynyl group, an aryl group such as a phenyl group or a tolyl group,a hydroxyl group, a carboxyl group, a sulfonate group, a carbonyl group,a cyano group or the like.

As particular examples of the groups each comprising a cycloaliphaticgroup or a noncyclic hydrocarbon group represented by A, the followingstructures are preferred from the viewpoint of inhibiting any aciddiffusion.

In the formula, p is an integer of 0 or greater. There is no particularupper limit as long as the number is chemically feasible. From theviewpoint of inhibiting any acid diffusion, p is generally in the rangeof 0 to 5, preferably 1 to 4, more preferably 2 or 3 and most preferably3.

Further, from the viewpoint of inhibiting any acid diffusion, thesubstitution with A-group preferably occurs at least one o-position tothe sulfonic acid group, more preferably at two o-positions to thesulfonic acid group.

The acid generator (B) according to the present invention in its oneform is a compound that generates any of acids of general formula (BII)below.

In the formula, A is as defined above in connection with general formula(BI). Two A's may be identical to or different from each other. Each ofR₁ to R₃ independently represents a hydrogen atom, a group comprising ahydrocarbon group, a halogen atom, a hydroxyl group, a cyano group or anitro group. As particular examples of the groups each comprising ahydrocarbon group, there can be mentioned the same groups as set forthabove by way of example.

Further, as preferred sulfonate anions, there can be mentioned theanions that generate the acids of general formula (I) below.

In the formula, each of Xfs independently represents a fluorine atom oran alkyl group substituted with at least one fluorine atom. Each of R¹and R² independently represents a member selected from among a hydrogenatom, a fluorine atom and an alkyl group. When two or more R¹s or R²sare contained, the two or more may be identical to or different fromeach other. L represents a bivalent connecting group. When two or moreLs are contained, they may be identical to or different from each other.A represents an organic group with a cyclic structure. In the formula, xis an integer of 1 to 20, y an integer of 0 to 10 and z an integer of 0to 10.

General formula (I) will be described in greater detail below.

The alkyl group of the alkyl group substituted with a fluorine atom,represented by Xf preferably has 1 to 10 carbon atoms, more preferably 1to 4 carbon atoms. The alkyl group substituted with a fluorine atom,represented by Xf is preferably a perfluoroalkyl group.

Xf is preferably a fluorine atom or CF₃. It is especially preferred thatboth Xfs are fluorine atoms.

Each of the alkyl group represented by each of R¹ and R² may have asubstituent (preferably a fluorine atom), and preferably has 1 to 4carbon atoms.

Each of R¹ and R² is preferably a fluorine atom or CF₃.

In the formula, y is preferably 0 to 4, more preferably 0; x ispreferably 1 to 8, more preferably 1 to 4; and z is preferably 0 to 8,more preferably 0 to 4. The bivalent connecting group represented by Lis not particularly limited. As the same, there can be mentioned, forexample, any one or a combination of two or more groups selected fromthe group consisting of —COO—, —OCO—, —CO—, —O—, —S—, —SO—, —SO₂—, analkylene group, a cycloalkylene group and an alkenylene group. The sumof carbon atoms of the bivalent connecting group represented by L ispreferably 12 or less. Of these, —COO—, —OCO—, —CO—, —O— and —SO₂— arepreferred. —COO—, —OCO— and —SO₂— are more preferred.

The organic group with a cyclic structure represented by A is notparticularly limited. As the group, there can be mentioned an alicyclicgroup, an aryl group, a heterocyclic group (including not only thoseexhibiting aromaticity but also those exhibiting no aromaticity) or thelike.

The alicyclic group may be monocyclic or polycyclic. Preferably, thealicyclic group is a cycloalkyl group of a single ring, such as acyclopentyl group, a cyclohexyl group or a cyclooctyl group, or acycloalkyl group of multiple rings, such as a norbornyl group, atricyclodecanyl group, a tetracyclodecanyl group, a tetracyclododecanylgroup or an adamantyl group. Of the mentioned groups, alicyclic groupswith a bulky structure having at least 7 carbon atoms, namely, anorbornyl group, a tricyclodecanyl group, a tetracyclodecanyl group, atetracyclododecanyl group and an adamantyl group are preferred from theviewpoint of inhibiting any in-film diffusion in the step ofpost-exposure bake (PEB) to thereby enhance Mask Error EnhancementFactor (MEEF).

As the aryl group, there can be mentioned a benzene ring, a naphthalenering, a phenanthrene ring or an anthracene ring. Naphthalene exhibitinga low absorbance is especially preferred from the viewpoint of theabsorbance at 193 nm.

As the heterocyclic groups, there can be mentioned those derived from afuran ring, a thiophene ring, a benzofuran ring, a benzothiophene ring,a dibenzofuran ring, a dibenzothiophene ring, a pyridine ring and apiperidine ring. Of these, the groups derived from a furan ring, athiophene ring, a pyridine ring and a piperidine ring are preferred.

As the cyclic organic groups, there can also be mentioned lactonestructures. As particular examples thereof, there can be mentioned theabove lactone structures of general formulae (LC1-1) to (LC1-17) thatmay be incorporated in the resin (A).

A substituent may be introduced in each of the above cyclic organicgroups. As the substituent, there can be mentioned an alkyl group (maybe linear or branched, preferably having 1 to 12 carbon atoms), acycloalkyl group (may be in the form of any of a monocycle, a polycycleand a spiro ring, preferably having 3 to 20 carbon atoms), an aryl group(preferably having 6 to 14 carbon atoms), a hydroxyl group, an alkoxygroup, an ester group, an amido group, a urethane group, a ureido group,a thioether group, a sulfonamido group, a sulfonic ester group or thelike. The carbon as a constituent of any of the cyclic organic groups(carbon contributing to the formation of a ring) may be a carbonylcarbon.

As the aliphatic moiety of the aliphatic carboxylate anion, there can bementioned the same alkyl groups and cycloalkyl groups as mentioned withrespect to the aliphatic sulfonate anion.

As the aromatic group of the aromatic carboxylate anion, there can bementioned the same aryl groups as mentioned with respect to the aromaticsulfonate anion.

As a preferred aralkyl group of the aralkyl carboxylate anion, there canbe mentioned an aralkyl group having 7 to 12 carbon atoms, for example,a benzyl group, a phenethyl group, a naphthylmethyl group, anaphthylethyl group, a naphthylbutyl group or the like.

The alkyl group, cycloalkyl group, aryl group and aralkyl group of thealiphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion may have a substituent. As the substituent of thealkyl group, cycloalkyl group, aryl group and aralkyl group of thealiphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion, there can be mentioned, for example, the same halogenatom, alkyl group, cycloalkyl group, alkoxy group, alkylthio group, etc.as mentioned with respect to the aromatic sulfonate anion.

As the sulfonylimido anion, there can be mentioned, for example, asaccharin anion.

The alkyl group of the bis(alkylsulfonyl)imido anion andtris(alkylsulfonyl)methide anion is preferably an alkyl group having 1to 5 carbon atoms. As such, there can be mentioned, for example, amethyl group, an ethyl group, a propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a pentyl group, aneopentyl group or the like. As a substituent of these alkyl groups,there can be mentioned a halogen atom, an alkyl group substituted with ahalogen atom, an alkoxy group, an alkylthio group, an alkyloxysulfonylgroup, an aryloxysulfonyl group, a cycloalkylaryloxysulfonyl group orthe like. An alkyl group substituted with a fluorine atom is preferred.

The two alkyl groups contained in the bis(alkylsulfonyl)imide anion maybe identical to or different from each other. Similarly, the multiplealkyl groups contained in the tris(alkylsulfonyl)methide anion may beidentical to or different from each other.

In particular, as the bis(alkylsulfonyl)imide anion andtris(alkylsulfonyl)methide anion, there can be mentioned the anions ofgeneral formulae (A3) and (A4) below.

In general formulae (A3) and (A4),

Y represents an alkylene group substituted with at least one fluorineatom, preferably having 2 to 4 carbon atoms. An oxygen atom may becontained in the alkylene chain. More preferably, Y is aperfluoroalkylene group having 2 to 4 carbon atoms. Most preferably, Yis a tetrafluoroethylene group, a hexafluoropropylene group or anoctafluorobutylene group.

In formula (A4), R represents an alkyl group or a cycloalkyl group. Anoxygen atom may be contained in the alkylene chain of the alkyl group orcycloalkyl group.

As the compounds containing the anions of general formulae (A3) and(A4), there can be mentioned, for example, particular examples set forthin JP-A-2005-221721.

As the other normucleophilic anions, there can be mentioned, forexample, phosphorus fluoride, boron fluoride, antimony fluoride and thelike.

As the organic groups represented by R₂₀₁, R₂₀₂ and R₂₀₃ of generalformula (ZI), there can be mentioned, for example, groups correspondingto the following compounds (ZI-1), (ZI-2), (ZI-3) and (ZI-4).

Appropriate use may be made of compounds with two or more of thestructures of general formula (ZI). For example, use may be made ofcompounds having a structure wherein at least one of R₂₀₁ to R₂₀₃ of acompound of general formula (ZI) is bonded with at least one of R₂₀₁ toR₂₀₃ of another compound of general formula (ZI).

As more preferred (ZI) components, there can be mentioned the followingcompounds (ZI-1), (ZI-2), (ZI-3) and (ZI-4).

The compounds (ZI-1) are arylsulfonium compounds of general formula (ZI)wherein at least one of R₂₀₁ to R₂₀₃ is an aryl group, namely, compoundscontaining an arylsulfonium as a cation.

In the arylsulfonium compounds, all of the R₂₀₁ to R₂₀₃ may be arylgroups. It is also appropriate that the R₂₀₁ to R₂₀₃ are partially anaryl group and the remainder is an alkyl group or a cycloalkyl group.

As the arylsulfonium compounds, there can be mentioned, for example, atriarylsulfonium compound, a diarylalkylsulfonium compound, anaryldialkylsulfonium compound, a diarylcycloalkylsulfonium compound andan aryldicycloalkylsulfonium compound.

The aryl group of the arylsulfonium compounds is preferably a phenylgroup or a naphthyl group, more preferably a phenyl group. The arylgroup may be one having a heterocyclic structure containing an oxygenatom, nitrogen atom, sulfur atom or the like. As the aryl group having aheterocyclic structure, there can be mentioned, for example, a pyrroleresidue, a furan residue, a thiophene residue, an indole residue, abenzofuran residue, a benzothiophene residue or the like. When thearylsulfonium compound has two or more aryl groups, the two or more arylgroups may be identical to or different from each other.

The alkyl group or cycloalkyl group contained in the arylsulfoniumcompound according to necessity is preferably a linear or branched alkylgroup having 1 to 15 carbon atoms or a cycloalkyl group having 3 to 15carbon atoms. As such, there can be mentioned, for example, a methylgroup, an ethyl group, a propyl group, an n-butyl group, a sec-butylgroup, a t-butyl group, a cyclopropyl group, a cyclobutyl group, acyclohexyl group or the like.

The aryl group, alkyl group or cycloalkyl group represented by R₂₀₁ toR₂₀₃ may have as its substituent an alkyl group (for example, 1 to 15carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms),an aryl group (for example, 6 to 14 carbon atoms), an alkoxy group (forexample, 1 to 15 carbon atoms), a halogen atom, a hydroxyl group or aphenylthio group. Preferred substituents are a linear or branched alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12carbon atoms and a linear, branched or cyclic alkoxy group having 1 to12 carbon atoms. More preferred substituents are an alkyl group having 1to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. Thesubstituents may be contained in any one of the three R₂₀₁ to R₂₀₃, oralternatively may be contained in all three of R₂₀₁ to R₂₀₃. When R₂₀₁to R₂₀₃ represent an aryl group, the substituent preferably lies at thep-position of the aryl group.

Now, the compounds (ZI-2) will be described.

The compounds (ZI-2) are compounds of formula (ZI) wherein each of R₂₀₁to R₂₀₃ independently represents an organic group having no aromaticring. The aromatic rings include an aromatic ring having a heteroatom.

The organic group having no aromatic ring represented by R₂₀₁ to R₂₀₃generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.

Preferably, each of R₂₀₁ to R₂₀₃ independently represents an alkylgroup, a cycloalkyl group, an allyl group or a vinyl group. Morepreferred groups are a linear or branched 2-oxoalkyl group, a2-oxocycloalkyl group and an alkoxycarbonylmethyl group. Especiallypreferred is a linear or branched 2-oxoalkyl group.

As preferred alkyl groups and cycloalkyl groups represented by R₂₀₁ toR₂₀₃, there can be mentioned a linear or branched alkyl group having 1to 10 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms.As more preferred alkyl groups, there can be mentioned a 2-oxoalkylgroup and an alkoxycarbonylmethyl group. As more preferred cycloalkylgroup, there can be mentioned a 2-oxocycloalkyl group.

The 2-oxoalkyl group may be linear or branched. A group having >C═O atthe 2-position of the alkyl group is preferred.

The 2-oxocycloalkyl group is preferably a group having >C═O at the2-position of the cycloalkyl group.

As preferred alkoxy groups of the alkoxycarbonylmethyl group, there canbe mentioned alkoxy groups having 1 to 5 carbon atoms.

The R₂₀₁ to R₂₀₃ may be further substituted with a halogen atom, analkoxy group (for example, 1 to 5 carbon atoms), a hydroxyl group, acyano group or a nitro group.

The compounds (ZI-3) are those represented by the following generalformula (ZI-3) which have a phenacylsulfonium salt structure.

In general formula (ZI-3),

each of R_(1c) to R_(5c) independently represents a hydrogen atom, analkyl group, a cycloalkyl group, an alkoxy group, a halogen atom or aphenylthio group.

Each of R_(6c) and R_(7c) independently represents a hydrogen atom, analkyl group, a cycloalkyl group, halogen atom, a cyano group or an arylgroup.

Each of R_(x) and R_(y) independently represents an alkyl group, acycloalkyl group, a 2-oxoalkyl group, a 2-oxocycloalkyl group, analkoxycarbonylalkyl group, an allyl group or a vinyl group.

Any two or more of R_(1c) to R_(5c), and R_(6c) and R_(7c), and R_(x)and R_(y) may be bonded with each other to thereby form a ringstructure. This ring structure may contain an oxygen atom, a sulfuratom, an ester bond or an amido bond. As the group formed by bonding ofany two or more of R_(1c) to R_(5c), and R_(6c) and R_(7c), and R_(x)and R_(y), there can be mentioned a butylene group, a pentylene group orthe like.

Zc⁻ represents a normucleophilic anion. There can be mentioned the samenormucleophilic anions as mentioned with respect to the Z⁻ of thegeneral formula (ZI).

The alkyl group represented by R_(1c) to R_(7c) may be linear orbranched. As such, there can be mentioned, for example, an alkyl grouphaving 1 to 20 carbon atoms, preferably a linear or branched alkyl grouphaving 1 to 12 carbon atoms (for example, a methyl group, an ethylgroup, a linear or branched propyl group, a linear or branched butylgroup or a linear or branched pentyl group). As the cycloalkyl group,there can be mentioned, for example, a cycloalkyl group having 3 to 8carbon atoms (for example, a cyclopentyl group or a cyclohexyl group).

The alkoxy group represented by R_(1c) to R_(5c) may be linear, orbranched, or cyclic. As such, there can be mentioned, for example, analkoxy group having 1 to 10 carbon atoms, preferably a linear orbranched alkoxy group having 1 to 5 carbon atoms (for example, a methoxygroup, an ethoxy group, a linear or branched propoxy group, a linear orbranched butoxy group or a linear or branched pentoxy group) and acycloalkoxy group having 3 to 8 carbon atoms (for example, acyclopentyloxy group or a cyclohexyloxy group).

Preferably, any one of R_(1c) to R_(5c) is a linear or branched alkylgroup, a cycloalkyl group or a linear, branched or cyclic alkoxy group.More preferably, the sum of carbon atoms of R_(1c) to R_(5c) is in therange of 2 to 15. Accordingly, there can be attained an enhancement ofsolvent solubility and inhibition of particle generation during storage.

Each of the aryl groups represented by R_(6c) and R_(7c) preferably has5 to 15 carbon atoms. As such, there can be mentioned, for example, aphenyl group or a naphthyl group.

When R_(6c) and R_(7c) are bonded to each other to thereby form a ring,the group formed by the bonding of R_(6c) and R_(7c) is preferably analkylene group having 2 to 10 carbon atoms. As such, there can bementioned, for example, an ethylene group, a propylene group, a butylenegroup, a pentylene group, a hexylene group or the like. Further, thering formed by the bonding of R_(6c) and R_(7c) may have a heteroatom,such as an oxygen atom, in the ring.

As the alkyl groups and cycloalkyl groups represented by R_(x) andR_(y), there can be mentioned the same alkyl groups and cycloalkylgroups as set forth above with respect to R_(1c) to R_(7c).

As the 2-oxoalkyl group and 2-oxocycloalkyl group, there can bementioned the alkyl group and cycloalkyl group represented by R_(1c) toR_(7c) having >C═O at the 2-position thereof.

With respect to the alkoxy group of the alkoxycarbonylalkyl group, therecan be mentioned the same alkoxy groups as mentioned above with respectto R_(1c) to R_(5c). As the alkyl group thereof, there can be mentioned,for example, an alkyl group having 1 to 12 carbon atoms, preferably alinear alkyl group having 1 to 5 carbon atoms (e.g., a methyl group oran ethyl group).

The allyl groups are not particularly limited. However, preferred use ismade of an unsubstituted allyl group or an allyl group substituted witha cycloalkyl group of a single ring or multiple rings.

The vinyl groups are not particularly limited. However, preferred use ismade of an unsubstituted vinyl group or a vinyl group substituted with acycloalkyl group of a single ring or multiple rings.

As the ring structure that may be formed by the mutual bonding of R_(x)and R_(y), there can be mentioned a 5-membered or 6-membered ring,especially preferably a 5-membered ring (namely, a tetrahydrothiophenering), formed by bivalent R_(x) and R_(y) (for example, a methylenegroup, an ethylene group, a propylene group or the like) in cooperationwith the sulfur atom of general formula (ZI-3).

Each of R_(x) and R_(y) is preferably an alkyl group or cycloalkyl grouphaving preferably 4 or more carbon atoms. The alkyl group or cycloalkylgroup has more preferably 6 or more carbon atoms and still morepreferably 8 or more carbon atoms.

Specific examples of the cations of the compounds (ZI-3) will be shownbelow.

The compounds (ZI-4) are those of general formula (ZI-4) below.

In general formula (ZI-4),

R₁₃ represents any of a hydrogen atom, a fluorine atom, a hydroxylgroup, an alkyl group, a cycloalkyl group, an alkoxy group, analkoxycarbonyl group and a group with a cycloalkyl skeleton of a singlering or multiple rings. These groups may have substituents.

R₁₄, each independently in the instance of R₁₄s, represents any of analkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonylgroup, an alkylcarbonyl group, an alkylsulfonyl group, acycloalkylsulfonyl group and a group with a cycloalkyl skeleton of asingle ring or multiple rings. These groups may have substituents.

Each of R₁₅s independently represents an alkyl group, a cycloalkyl groupor a naphthyl group, provided that the two R₁₅s may be bonded to eachother to thereby form a ring. These groups may have substituents.

In the formula, 1 is an integer of 0 to 2, and

r is an integer of 0 to 8.

Z⁻ represents a normucleophilic anion. As such, there can be mentionedany of the same normucleophilic anions as mentioned with respect to theZ⁻ of the general formula (ZI).

In general formula (ZI-4), the alkyl groups represented by R₁₃, R₁₄ andR₁₅ may be linear or branched and preferably each have 1 to 10 carbonatoms. As such, there can be mentioned a methyl group, an ethyl group,an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropylgroup, a 1-methylpropyl group, a t-butyl group, an n-pentyl group, aneopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group,a 2-ethylhexyl group, an n-nonyl group, an n-decyl group and the like.Of these alkyl groups, a methyl group, an ethyl group, an n-butyl group,a t-butyl group and the like are preferred.

The cycloalkyl groups represented by R₁₃, R₁₄ and R₁₅ include acycloalkylene group. As the cycloalkyl groups, there can be mentionedcyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl,cyclooctadienyl, norbornyl, tricyclodecanyl, tetracyclodecanyl,adamantyl and the like. Cyclopropyl, cyclopentyl, cyclohexyl andcyclooctyl are especially preferred.

The alkoxy groups represented by R₁₃ and R₁₄ may be linear or branchedand preferably each have 1 to 10 carbon atoms. As such, there can bementioned, for example, a methoxy group, an ethoxy group, an n-propoxygroup, an i-propoxy group, an n-butoxy group, a 2-methylpropoxy group, a1-methylpropoxy group, a t-butoxy group, an n-pentyloxy group, aneopentyloxy group, an n-hexyloxy group, an n-heptyloxy group, ann-octyloxy group, a 2-ethylhexyloxy group, an n-nonyloxy group, ann-decyloxy group and the like. Of these alkoxy groups, a methoxy group,an ethoxy group, an n-propoxy group, an n-butoxy group and the like arepreferred.

The alkoxycarbonyl group represented by R₁₃ and R₁₄ may be linear orbranched and preferably has 2 to 11 carbon atoms. As such, there can bementioned, for example, a methoxycarbonyl group, an ethoxycarbonylgroup, an n-propoxycarbonyl group, an i-propoxycarbonyl group, ann-butoxycarbonyl group, a 2-methylpropoxycarbonyl group, a1-methylpropoxycarbonyl group, a t-butoxycarbonyl group, ann-pentyloxycarbonyl group, a neopentyloxycarbonyl group, ann-hexyloxycarbonyl group, an n-heptyloxycarbonyl group, ann-octyloxycarbonyl group, a 2-ethylhexyloxycarbonyl group, ann-nonyloxycarbonyl group, an n-decyloxycarbonyl group and the like. Ofthese alkoxycarbonyl groups, a methoxycarbonyl group, an ethoxycarbonylgroup, an n-butoxycarbonyl group and the like are preferred.

As the groups with a cycloalkyl skeleton of a single ring or multiplerings represented by R₁₃ and R₁₄, there can be mentioned, for example, acycloalkyloxy group of a single ring or multiple rings and an alkoxygroup with a cycloalkyl group of a single ring or multiple rings. Thesegroups may further have substituents.

With respect to each of the cycloalkyloxy groups of a single ring ormultiple rings represented by R₁₃ and R₁₄, the sum of carbon atomsthereof is preferably 7 or greater, more preferably in the range of 7 to15. Further, having a cycloalkyl skeleton of a single ring is preferred.The cycloalkyloxy group of a single ring of which the sum of carbonatoms is 7 or greater is one composed of a cycloalkyloxy group, such asa cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, acyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group or acyclododecanyloxy group, optionally having a substituent selected fromamong an alkyl group such as methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, dodecyl, 2-ethylhexyl, isopropyl, sec-butyl,t-butyl or isoamyl, a hydroxyl group, a halogen atom (fluorine,chlorine, bromine or iodine), a nitro group, a cyano group, an amidogroup, a sulfonamido group, an alkoxy group such as methoxy, ethoxy,hydroxyethoxy, propoxy, hydroxypropoxy or butoxy, an alkoxycarbonylgroup such as methoxycarbonyl or ethoxycarbonyl, an acyl group such asformyl, acetyl or benzoyl, an acyloxy group such as acetoxy orbutyryloxy, a carboxyl group and the like, provided that the sum ofcarbon atoms thereof, including those of any optional substituentintroduced in the cycloalkyl group, is 7 or greater.

As the cycloalkyloxy group of multiple rings of which the sum of carbonatoms is 7 or greater, there can be mentioned a norbornyloxy group, atricyclodecanyloxy group, a tetracyclodecanyloxy group, an adamantyloxygroup or the like.

With respect to each of the alkyloxy groups having a cycloalkyl skeletonof a single ring or multiple rings represented by R₁₃ and R₁₄, the sumof carbon atoms thereof is preferably 7 or greater, more preferably inthe range of 7 to 15. Further, the alkoxy group having a cycloalkylskeleton of a single ring is preferred. The alkoxy group having acycloalkyl skeleton of a single ring of which the sum of carbon atoms is7 or greater is one composed of an alkoxy group, such as methoxy,ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptoxy, octyloxy,dodecyloxy, 2-ethylhexyloxy, isopropoxy, sec-butoxy, t-butoxy orisoamyloxy, substituted with the above optionally substituted cycloalkylgroup of a single ring, provided that the sum of carbon atoms thereof,including those of the substituents, is 7 or greater. For example, therecan be mentioned a cyclohexylmethoxy group, a cyclopentylethoxy group, acyclohexylethoxy group or the like. A cyclohexylmethoxy group ispreferred.

As the alkoxy group having a cycloalkyl skeleton of multiple rings ofwhich the sum of carbon atoms is 7 or greater, there can be mentioned anorbornylmethoxy group, a norbornylethoxy group, atricyclodecanylmethoxy group, a tricyclodecanylethoxy group, atetracyclodecanylmethoxy group, a tetracyclodecanylethoxy group, anadamantylmethoxy group, an adamantylethoxy group and the like. Of these,a norbornylmethoxy group, a norbornylethoxy group and the like arepreferred.

With respect to the alkyl group of the alkylcarbonyl group representedby R₁₄, there can be mentioned the same specific examples as mentionedabove with respect to the alkyl groups represented by R₁₃ to R₁₅.

The alkylsulfonyl and cycloalkylsulfonyl groups represented by R₁₄ maybe linear, branched or cyclic and preferably each have 1 to 10 carbonatoms. As such, there can be mentioned, for example, a methanesulfonylgroup, an ethanesulfonyl group, an n-propanesulfonyl group, ann-butanesulfonyl group, a tert-butanesulfonyl group, ann-pentanesulfonyl group, a neopentanesulfonyl group, an n-hexanesulfonylgroup, an n-heptanesulfonyl group, an n-octanesulfonyl group, a2-ethylhexanesulfonyl group, an n-nonanesulfonyl group, ann-decanesulfonyl group, a cyclopentanesulfonyl group, acyclohexanesulfonyl group and the like. Of these alkylsulfonyl andcycloalkylsulfonyl groups, a methanesulfonyl group, an ethanesulfonylgroup, an n-propanesulfonyl group, an n-butanesulfonyl group, acyclopentanesulfonyl group, a cyclohexanesulfonyl group and the like arepreferred.

Each of the groups may have a substituent. As such a substituent, therecan be mentioned, for example, a halogen atom (e.g., a fluorine atom), ahydroxyl group, a carboxyl group, a cyano group, a nitro group, analkoxy group, an alkoxyalkyl group, an alkoxycarbonyl group, analkoxycarbonyloxy group or the like.

As the alkoxy group, there can be mentioned, for example, a linear,branched or cyclic alkoxy group having 1 to 20 carbon atoms, such as amethoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group,an n-butoxy group, a 2-methylpropoxy group, a 1-methylpropoxy group, at-butoxy group, a cyclopentyloxy group or a cyclohexyloxy group.

As the alkoxyalkyl group, there can be mentioned, for example, a linear,branched or cyclic alkoxyalkyl group having 2 to 21 carbon atoms, suchas a methoxymethyl group, an ethoxymethyl group, a 1-methoxyethyl group,a 2-methoxyethyl group, a 1-ethoxyethyl group or a 2-ethoxyethyl group.

As the alkoxycarbonyl group, there can be mentioned, for example, alinear, branched or cyclic alkoxycarbonyl group having 2 to 21 carbonatoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, ann-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonylgroup, a 2-methylpropoxycarbonyl group, a 1-methylpropoxycarbonyl group,a t-butoxycarbonyl group, a cyclopentyloxycarbonyl group or acyclohexyloxycarbonyl group.

As the alkoxycarbonyloxy group, there can be mentioned, for example, alinear, branched or cyclic alkoxycarbonyloxy group having 2 to 21 carbonatoms, such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group,an n-propoxycarbonyloxy group, an i-propoxycarbonyloxy group, ann-butoxycarbonyloxy group, a t-butoxycarbonyloxy group, acyclopentyloxycarbonyloxy group or a cyclohexyloxycarbonyloxy group.

The cyclic structure that may be formed by the bonding of the two R₁₅sto each other is preferably a 5- or 6-membered ring, especially a5-membered ring (namely, a tetrahydrothiophene ring) formed by twobivalent R₁₅s in cooperation with the sulfur atom of general formula(ZI-4). The cyclic structure may condense with an aryl group or acycloalkyl group. The bivalent R₁₅s may have substituents. As suchsubstituents, there can be mentioned, for example, a hydroxyl group, acarboxyl group, a cyano group, a nitro group, an alkoxy group, analkoxyalkyl group, an alkoxycarbonyl group, an alkoxycarbonyloxy groupand the like as mentioned above. It is especially preferred for the R₁₅of general formula (ZI-4) to be a methyl group, an ethyl group, theabove-mentioned bivalent group allowing two R₁₅s to be bonded to eachother so as to form a tetrahydrothiophene ring structure in cooperationwith the sulfur atom of the general formula (ZI-4), or the like.

Each of R₁₃ and R₁₄ may have a substituent. As such a substituent, therecan be mentioned, for example, a hydroxyl group, an alkoxy group, analkoxycarbonyl group, a halogen atom (especially, a fluorine atom) orthe like.

In the formula, 1 is preferably 0 or 1, more preferably 1, and r ispreferably 0 to 2.

Specific examples of the cations of the compounds (ZI-4) will be shownbelow.

In general formulae (ZII) and (ZIII), each of R₂₀₄ to R₂₀₇ independentlyrepresents an aryl group, an alkyl group or a cycloalkyl group.

The aryl group represented by R₂₀₄ to R₂₀₇ is preferably a phenyl groupor a naphthyl group, more preferably a phenyl group. The aryl grouprepresented by R₂₀₄ to R₂₀₇ may be one having a heterocyclic structurecontaining an oxygen atom, nitrogen atom, sulfur atom or the like. Asthe heterocyclic structure, there can be mentioned, for example, apyrrole, a furan, a thiophene, an indole, a benzofuran, a benzothiopheneor the like.

As preferred alkyl groups and cycloalkyl groups represented by R₂₀₄ toR₂₀₇, there can be mentioned a linear or branched alkyl group having 1to 10 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms.

The aryl group, alkyl group and cycloalkyl group represented by R₂₀₄ toR₂₀₇ may have a substituent. As a possible substituent on the arylgroup, alkyl group and cycloalkyl group represented by R₂₀₄ to R₂₀₇,there can be mentioned, for example, an alkyl group (for example, 1 to15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbonatoms), an aryl group (for example, 6 to 15 carbon atoms), an alkoxygroup (for example, 1 to 15 carbon atoms), a halogen atom, a hydroxylgroup, a phenylthio group or the like.

Z⁻ represents a normucleophilic anion. As such, there can be mentionedthe same normucleophilic anions as mentioned with respect to the Z⁻ ofthe general formula (ZI).

As the acid generators, there can be further mentioned the compounds ofthe following general formulae (ZIV), (ZV) and (ZVI).

In the general formulae (ZIV) to (ZVI),

each of Ar₃ and Ar₄ independently represents an aryl group.

Each of R₂₀₈, R₂₀₉ and R₂₁₀ independently represents an alkyl group, acycloalkyl group or an aryl group.

A represents an alkylene group, an alkenylene group or an arylene group.

As specific examples of the aryl groups represented by Ar₃, Ar₄, R₂₀₈,R₂₀₉ and R₂₁₀, there can be mentioned the same groups as mentioned withrespect to the aryl groups represented by R₂₀₁, R₂₀₂ and R₂₀₃ of generalformula (ZI-1) above.

As specific examples of each of the alkyl groups and the cycloalkylgroups represented by R₂₀₈, R₂₀₉ and R₂₁₀, there can be mentioned thesame groups as mentioned with respect to each of the alkyl groups andthe cycloalkyl groups represented by R₂₀₁, R₂₀₂ and R₂₀₃ of generalformula (ZI-1) above.

As the alkylene group represented by A, there can be mentioned analkylene group having 1 to 12 carbon atoms such as a methylene group, anethylene group, a propylene group, an isopropylene group, a butylenegroup, an isobutylene group or the like. As the alkenylene grouprepresented by A, there can be mentioned an alkenylene group having 2 to12 carbon atoms such as an ethynylene group, a propenylene group, abutenylene group or the like. As the arylene group represented by A,there can be mentioned an arylene group having 6 to 10 carbon atoms suchas a phenylene group, a tolylene group, a naphthylene group or the like.

Among the acid generators, the compounds of the general formulae (ZI) to(ZIII) are more preferred.

Especially preferred examples of the acid generators are as follows.

The acid generators can be used alone or in combination. The content ofacid generator in the composition is preferably in the range of 0.1 to20 mass %, more preferably 0.5 to 10 mass %, and still more preferably 1to 7 mass % based on the total solids of the actinic-ray- orradiation-sensitive resin composition.

[3-3] Crosslinking Agent (C)

The resist composition according to the present invention may contain,together with the resin (A), a compound (hereinafter referred to as acrosslinking agent) capable of crosslinking the resin (A) under theaction of an acid. In the present invention, heretofore knowncrosslinking agents can be effectively used. When the crosslinking agentis used, as mentioned hereinbefore, it is preferred for the resin (A) tocontain a repeating unit (a2) containing an alcoholic hydroxyl group.

The crosslinking agent (C) is a compound containing a crosslinking groupcapable of crosslinking the resin (A). As the crosslinking group, therecan be mentioned a hydroxymethyl group, an alkoxymethyl group, a vinylether group, an epoxy group or the like. It is preferred for thecrosslinking agent (C) to have two or more such crosslinking groups.

The crosslinking agent (C) is preferably one consisting of a melaminecompound, a urea compound, an alkyleneurea compound or a glycolurilcompound.

Specific examples of the crosslinking agent (C) will be shown below,which however in no way limit the scope of the present invention.

In the present invention, each of these crosslinking agents may be usedalone, or two or more thereof may be used in combination.

When the resist composition contains a crosslinking agent, the contentof the crosslinking agent in the resist composition is preferably in therange of 3 to 15 mass %, more preferably 4 to 12 mass % and further morepreferably 5 to 10 mass % based on the total solids of the resistcomposition.

[3-4] Solvent (D)

The actinic-ray- or radiation-sensitive resin composition of the presentinvention contains a solvent.

The solvent is not limited as long as it can be used in the preparationof the composition. As the solvent, there can be mentioned, for example,an organic solvent, such as an alkylene glycol monoalkyl ethercarboxylate, an alkylene glycol monoalkyl ether, an alkyl lactate, analkyl alkoxypropionate, a cyclolactone (preferably having 4 to 10 carbonatoms), an optionally cyclized monoketone compound (preferably having 4to 10 carbon atoms), an alkylene carbonate, an alkyl alkoxyacetate or analkyl pyruvate.

Particular examples and preferred examples of the solvents are the sameas those described in [0244] to [0248] of JP-A-2008-292975.

In the present invention, a mixed solvent consisting of a mixture of asolvent having a hydroxyl group in its structure and a solvent having nohydroxyl group may be used as the organic solvent.

The solvent having a hydroxyl group and the solvent having no hydroxylgroup can appropriately be selected from among the compounds mentionedabove, as examples. The solvent having a hydroxyl group is preferably analkylene glycol monoalkyl ether, an alkyl lactate or the like, morepreferably propylene glycol monomethyl ether (PGME, another name:1-methoxy-2-propanol) or ethyl lactate. The solvent having no hydroxylgroup is preferably an alkylene glycol monoalkyl ether acetate, an alkylalkoxypropionate, an optionally cyclized monoketone compound, acyclolactone, an alkyl acetate or the like. Among these, propyleneglycol monomethyl ether acetate (PGMEA, another name:1-methoxy-2-acetoxypropane), ethyl ethoxypropionate, 2-heptanone,γ-butyrolactone, cyclohexanone and butyl acetate are especiallypreferred. Propylene glycol monomethyl ether acetate, ethylethoxypropionate and 2-heptanone are most preferred.

The mixing ratio (mass) of a solvent having a hydroxyl group and asolvent having no hydroxyl group is commonly in the range of 1/99 to99/1, preferably 10/90 to 90/10 and more preferably 20/80 to 60/40. Themixed solvent containing 50 mass % or more of a solvent having nohydroxyl group is especially preferred from the viewpoint of uniformapplicability.

It is preferred for the solvent to be a mixed solvent consisting of twoor more solvents containing propylene glycol monomethyl ether acetate.

[3-5] Hydrophobic Resin (HR)

The composition of the present invention may further contain ahydrophobic resin (HR) containing at least either a fluorine atom or asilicon atom especially when a liquid immersion exposure is appliedthereto. This localizes the hydrophobic resin (HR) in the surface layerof the film. Accordingly, when the immersion medium is water, thestatic/dynamic contact angle of the surface of the resist film withrespect to water can be increased, thereby enhancing the immersion watertracking property.

Although the hydrophobic resin (HR) is unevenly localized in theinterface as mentioned above, as different from surfactants, thehydrophobic resin does not necessarily have to have a hydrophilic groupin its molecule and does not need to contribute toward uniform mixing ofpolar/nonpolar substances.

The hydrophobic resin typically contains a fluorine atom and/or asilicon atom. The fluorine atom and/or silicon atom may be introduced inthe principal chain of the resin or a side chain thereof.

When the hydrophobic resin contains a fluorine atom, it is preferred forthe resin to comprise, as a partial structure containing a fluorineatom, an alkyl group containing a fluorine atom, a cycloalkyl groupcontaining a fluorine atom or an aryl group containing a fluorine atom.

The alkyl group containing a fluorine atom is a linear or branched alkylgroup having at least one hydrogen atom thereof substituted with afluorine atom. This alkyl group preferably has 1 to 10 carbon atoms,more preferably 1 to 4 carbon atoms. A substituent other than thefluorine atom may further be introduced in the alkyl group containing afluorine atom.

The cycloalkyl group containing a fluorine atom is a mono- orpolycycloalkyl group having at least one hydrogen atom thereofsubstituted with a fluorine atom. A substituent other than the fluorineatom may further be introduced in the cycloalkyl group containing afluorine atom.

The aryl group containing a fluorine atom is an aryl group having atleast one hydrogen atom thereof substituted with a fluorine atom. As thearyl group, there can be mentioned, for example, a phenyl or naphthylgroup. A substituent other than the fluorine atom may further beintroduced in the aryl group containing a fluorine atom.

As preferred examples of the alkyl groups each containing a fluorineatom, cycloalkyl groups each containing a fluorine atom and aryl groupseach containing a fluorine atom, there can be mentioned the groups ofgeneral formulae (F2) to (F4) below.

In general formulae (F2) to (F4), each of R₅₇ to R₆₈ independentlyrepresents a hydrogen atom, a fluorine atom or an alkyl group, providedthat at least one of R₅₇ to R₆₁ represents a fluorine atom or an alkylgroup having at least one hydrogen atom thereof substituted with afluorine atom, provided that at least one of R₆₂ to R₆₄ represents afluorine atom or an alkyl group having at least one hydrogen atomthereof substituted with a fluorine atom, and provided that at least oneof R₆₅ to R₆₈ represents a fluorine atom or an alkyl group having atleast one hydrogen atom thereof substituted with a fluorine atom. It ispreferred for each of these alkyl groups to have 1 to 4 carbon atoms.

Specific examples of the repeating units having a fluorine atom will beshown below.

In the specific examples, X₁ represents a hydrogen atom, —CH₃, —F or—CF₃. X₂ represents —F or —CF₃.

When the hydrophobic resin contains a silicon atom, it is preferred forthe resin to comprise, as a partial structure containing a silicon atom,an alkylsilyl structure or a cyclosiloxane structure. This alkylsilylstructure is preferably a structure containing a trialkylsilyl group.

As preferred examples of the alkylsilyl structures and cyclosiloxanestructures, there can be mentioned the groups of general formulae (CS-1)to (CS-3) below.

In general formulae (CS-1) to (CS-3), each of R₁₂ to R₂₆ independentlyrepresents a linear or branched alkyl group or a cycloalkyl group. Thealkyl group is preferably one having 1 to 20 carbon atoms. Thecycloalkyl group is preferably one having 3 to 20 carbon atoms.

Each of L₃ to L₅ represents a single bond or a bivalent connectinggroup. As the bivalent connecting group, there can be mentioned any oneor a combination of two or more groups selected from the groupconsisting of an alkylene group, a phenylene group, an ether group, athioether group, a carbonyl group, an ester group, an amido group, aurethane group and a urea group.

In the formulae, n is an integer of 1 to 5, preferably an integer of 2to 4.

Specific examples of the repeating units having the groups of generalformulae (CS-1) to (CS-3) will be shown below.

In the specific examples, X₁ represents a hydrogen atom, —CH₃, —F or—CF₃.

The hydrophobic resin may further contain at least one group selectedfrom the group consisting of the following groups (x) to (z).

Namely,

(x) an acid group,

(y) a group with a lactone structure, an acid anhydride group or an acidimido group, and

(y) an acid-decomposable group.

As the acid group (x), there can be mentioned, for example, a phenolichydroxyl group, a carboxylic acid group, a fluoroalcohol group, asulfonic acid group, a sulfonamido group, a sulfonimido group, an(alkylsulfonyl)(alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkylcarbonyl)imido group, a bis(alkylcarbonyl)methylenegroup, a bis(alkylcarbonyl)imido group, a bis(alkylsulfonyl)methylenegroup, a bis(alkylsulfonyl)imido group, a tris(alkylcarbonyl)methylenegroup or a tris(alkylsulfonyl)methylene group. As preferred acid groups,there can be mentioned a fluoroalcohol group, a sulfonimido group and abis(alkylcarbonyl)methylene group. As a preferred fluoroalcohol group,there can be mentioned a hexafluoroisopropanol group.

The repeating unit containing an acid group is, for example, a repeatingunit wherein the acid group is directly bonded to the principal chain ofa resin, such as a repeating unit derived from acrylic acid ormethacrylic acid. Alternatively, this repeating unit may be a repeatingunit wherein the acid group is bonded via a connecting group to theprincipal chain of a resin. Still alternatively, this repeating unit maybe a repeating unit wherein the acid group is introduced in a terminalof the resin by using a chain transfer agent or polymerization initiatorcontaining the acid group in the stage of polymerization.

The content of the repeating unit containing an acid group based on allthe repeating units of the hydrophobic resin is preferably in the rangeof 1 to 50 mol %, more preferably 3 to 35 mol % and further morepreferably 5 to 20 mol %.

Particular examples of the repeating units each containing an acid groupare shown below. In the formulae, Rx represents a hydrogen atom, CH₃,CF₃ or CH₂OH.

Among the group with a lactone structure, acid anhydride group and acidimido group (y), the group with a lactone structure is especiallypreferred.

The repeating unit containing any of these groups is, for example, arepeating unit wherein the group is directly bonded to the principalchain of a resin, such as a repeating unit derived from an acrylic esteror a methacrylic ester. Alternatively, this repeating unit may be arepeating unit wherein the group is bonded via a connecting group to theprincipal chain of a resin. Still alternatively, this repeating unit maybe a repeating unit wherein the group is introduced in a terminal of theresin by using a chain transfer agent or polymerization initiatorcontaining the group in the stage of polymerization.

The repeating units each containing a group with a lactone structure canbe, for example, the same as the repeating units each with a lactonestructure described above in the section of the resin (A).

The content of the repeating unit containing a group with a lactonestructure, an acid anhydride group or an acid imido group, based on allthe repeating units of the hydrophobic resin, is preferably in the rangeof 1 to 40 mol %, more preferably 3 to 30 mol % and further morepreferably 5 to 15 mol %.

As the acid-decomposable group (z), there can be mentioned, for example,those set forth above in the section of the acid-decomposable resin (A).

The content of the repeating unit containing an acid-decomposable group,based on all the repeating units of the hydrophobic resin, is preferablyin the range of 1 to 80 mol %, more preferably 10 to 80 mol % andfurther more preferably 20 to 60 mol %.

The hydrophobic resin may contain any of the repeating units of generalformula (III′) below.

In general formula (III′),

R_(c31) represents a hydrogen atom, an alkyl group (optionallysubstituted with a fluorine atom or the like), a cyano group or—CH₂—O-Rac₂ group, wherein Rac₂ represents a hydrogen atom, an alkylgroup or an acyl group.

R_(c31) is preferably a hydrogen atom, a methyl group or atrifluoromethyl group, especially preferably a hydrogen atom or a methylgroup.

R_(c32) represents a group having any of an alkyl group, a cycloalkylgroup, an alkenyl group, a cycloalkenyl group and an aryl group. Theasegroups may optionally be substituted with a group having a fluorine atomor a silicon atom.

L_(c3) represents a single bond or a bivalent connecting group.

As the bivalent connecting group represented by L_(c3), there can bementioned, for example, an alkylene group (preferably having 1 to 5carbon atoms), an oxy group, a phenylene group, an ester bond (group ofthe formula —COO—), or a group comprising a combination of two or moreof these. The total number of carbon atoms in the bivalent connectinggroup is preferably in the range of 1 to 12.

The hydrophobic resin may contain any of the repeating units of generalformula (CII-AB) below.

In formula (CII-AB),

Each of R_(c11)′ and R_(c12)′ independently represents a hydrogen atom,a cyano group, a halogen atom or an alkyl group. Zc′ represents anatomic group required for forming an alicyclic structure in cooperationwith two carbon atoms (C—C) to which R_(c11)′ and R_(c12)′ arerespectively bonded.

R_(c32) is a substituent that is introduced in the alicyclic structure.The definition thereof is the same as that of R_(c32) of general formula(III′).

In the formula, p is an integer of 0 to 3, preferably 0 or 1.

Specific examples of the repeating units of general formula (III′) andgeneral formula (CII-AB) will be shown below. In the formulae, Rarepresents H, CH₃, CH₂OH, CF₃ or CN.

When the hydrophobic resin (HR) contains any of the repeating units ofgeneral formulae (III′) and (CII-AB), the content of such a repeatingunit, based on all the repeating units constructing the hydrophobicresin (HR), is preferably in the range of 1 to 100 mol %, morepreferably 5 to 95 mol % and further more preferably 20 to 80 mol %.

Specific examples of the hydrophobic resins (HR) will be shown below.The following Table 2 shows the molar ratio of individual repeatingunits (corresponding to individual repeating units in order from theleft), weight average molecular weight and degree of dispersal (Mw/Mn)with respect to each of the resins.

TABLE 1 Resin Composition Mw Mw/Mn HR-1 50/50 4900 1.4 HR-2 50/50 51001.6 HR-3 50/50 4800 1.5 HR-4 50/50 5300 1.6 HR-5 50/50 4500 1.4 HR-6 1005500 1.6 HR-7 50/50 5800 1.9 HR-8 50/50 4200 1.3 HR-9 50/50 5500 1.8HR-10 40/60 7500 1.6 HR-11 70/30 6600 1.8 HR-12 40/60 3900 1.3 HR-1350/50 9500 1.8 HR-14 50/50 5300 1.6 HR-15 100 6200 1.2 HR-16 100 56001.6 HR-17 100 4400 1.3 HR-18 50/50 4300 1.3 HR-19 50/50 6500 1.6 HR-2030/70 6500 1.5 HR-21 50/50 6000 1.6 HR-22 50/50 3000 1.2 HR-23 50/505000 1.5 HR-24 50/50 4500 1.4 HR-25 30/70 5000 1.4 HR-26 50/50 5500 1.6HR-27 50/50 3500 1.3 HR-28 50/50 6200 1.4 HR-29 50/50 6500 1.6 HR-3050/50 6500 1.6 HR-31 50/50 4500 1.4 HR-32 30/70 5000 1.6 HR-33 30/30/406500 1.8 HR-34 50/50 4000 1.3 HR-35 50/50 6500 1.7 HR-36 50/50 6000 1.5HR-37 50/50 5000 1.6 HR-38 50/50 4000 1.4 HR-39 20/80 6000 1.4 HR-4050/50 7000 1.4 HR-41 50/50 6500 1.6 HR-42 50/50 5200 1.6 HR-43 50/506000 1.4 HR-44 70/30 5500 1.6 HR-45 50/20/30 4200 1.4 HR-46 30/70 75001.6 HR-47 40/58/2 4300 1.4 HR-48 50/50 6800 1.6 HR-49 100 6500 1.5 HR-5050/50 6600 1.6 HR-51 30/20/50 6800 1.7 HR-52 95/5 5900 1.6 HR-5340/30/30 4500 1.3 HR-54 50/30/20 6500 1.8 HR-55 30/40/30 7000 1.5 HR-5660/40 5500 1.7 HR-57 40/40/20 4000 1.3 HR-58 60/40 3800 1.4 HR-59 80/207400 1.6 HR-60 40/40/15/5 4800 1.5 HR-61 60/40 5600 1.5 HR-62 50/50 59002.1 HR-63 80/20 7000 1.7 HR-64 100 5500 1.8 HR-65 50/50 9500 1.9

When the hydrophobic resin contains a fluorine atom, the content offluorine atom(s) is preferably in the range of 5 to 80 mass %, morepreferably 10 to 80 mass %, based on the molecular weight of thehydrophobic resin. The content of the repeating unit containing afluorine atom is preferably in the range of 10 to 100 mass %, morepreferably 30 to 100 mass %, based on all the repeating units of thehydrophobic resin.

When the hydrophobic resin contains a silicon atom, the content ofsilicon atom(s) is preferably in the range of 2 to 50 mass %, morepreferably 2 to 30 mass %, based on the molecular weight of thehydrophobic resin. The content of the repeating unit containing asilicon atom is preferably in the range of 10 to 100 mass %, morepreferably 20 to 100 mass %, based on all the repeating units of thehydrophobic resin.

The weight average molecular weight of the hydrophobic resin ispreferably in the range of 1000 to 100,000, more preferably 1000 to50,000 and still more preferably 2000 to 15,000.

From the viewpoint of resolving power, pattern profile, roughnessproperty, etc., the degree of dispersal of the hydrophobic resin ispreferably in the range of 1 to 5, more preferably 1 to 3 and still morepreferably 1 to 2.

The hydrophobic resins may be used either individually or incombination. The content of the hydrophobic resin in the composition ispreferably in the range or 0.01 to 10 mass %, more preferably 0.05 to 8mass % and still more preferably 0.1 to 5 mass % based on the totalsolid of the composition of the present invention.

A variety of commercially available products can be used as thehydrophobic resin, and also the resin can be synthesized in accordancewith conventional methods. As general synthesizing methods, there can bementioned, for example, the same method as mentioned with respect to theresin (A).

Impurities, such as metals, should naturally be of low quantity in thehydrophobic resin. The content of residual monomers and oligomercomponents is preferably 0 to 10 mass %, more preferably 0 to 5 mass %and still more preferably 0 to 1 mass %. Accordingly, there can beobtained a resist being free from a change of in-liquid foreign matter,sensitivity, etc. over time.

[3-6] Surfactant (F)

The composition of the present invention may further contain asurfactant. When the composition contains a surfactant, the compositionpreferably contains any one, or two or more members, of fluorinatedand/or siliconized surfactants (fluorinated surfactant, siliconizedsurfactant and surfactant containing both fluorine and silicon atoms).

The composition of the present invention when containing the abovesurfactant would, in the use of an exposure light source of 250 nm orbelow, especially 220 nm or below, realize favorable sensitivity andresolving power and produce a resist pattern with less adhesion anddevelopment defects.

As fluorinated and/or siliconized surfactants, there can be mentioned,for example, those described in section [0276] of US 2008/0248425 A1. Asuseful commercially available surfactants, there can be mentioned, forexample, fluorinated surfactants/siliconized surfactants, such as EftopEF301 and EF303 (produced by Shin-Akita Kasei Co., Ltd.), Florad FC 430,431 and 4430 (produced by Sumitomo 3M Ltd.), Megafac F171, F173, F176,F189, F113, F110, F177, F120 and R08 (produced by Dainippon Ink &Chemicals, Inc.), Surflon S-382, SC101, 102, 103, 104, 105 and 106(produced by Asahi Glass Co., Ltd.), Troy Sol S-366 (produced by TroyChemical Co., Ltd.), GF-300 and GF-150 (produced by TOAGOSEI CO., LTD.),Sarfron S-393 (produced by SEIMI CHEMICAL CO., LTD.), Eftop EF121,EF122A, EF122B, RF122C, EF125M, EF135M, EF351, EF352, EF801, EF802 andEF601 (produced by JEMCO INC.), PF636, PF656, PF6320 and PF6520(produced by OMNOVA), and FTX-204G, 208G, 218G, 230G, 204D, 208D, 212D,218D and 222D (produced by NEOS). Further, polysiloxane polymer KP-341(produced by Shin-Etsu Chemical Co., Ltd.) can be employed as thesiliconized surfactant.

As the surfactant, besides the above publicly known surfactants, use canbe made of a surfactant based on a polymer having a fluorinatedaliphatic group derived from a fluorinated aliphatic compound, producedby a telomerization technique (also called a telomer process) or anoligomerization technique (also called an oligomer process). Thefluorinated aliphatic compound can be synthesized by the processdescribed in JP-A-2002-90991.

As such a surfactant, there can be mentioned, for example, Megafac F178,F-470, F-473, F-475, F-476 or F-472 (produced by Dainippon Ink &Chemicals, Inc.). Further, there can be mentioned a copolymer from anacrylate (or methacrylate) having a C₆F₁₃ group and a poly(oxyalkylene)acrylate (or methacrylate), a copolymer from an acrylate (ormethacrylate) having a C₃F₇ group, poly(oxyethylene) acrylate (ormethacrylate) and poly(oxypropylene) acrylate (or methacrylate), or thelike.

In the present invention, surfactants other than the fluorinated and/orsiliconized surfactants can also be employed. In particular, there canbe mentioned, for example, those described in section [0280] of US2008/0248425 A1.

These surfactants may be used either individually or in combination.

When the composition contain the surfactant, the amount of thesurfactant used is preferably in the range of 0.0001 to 2 mass %, morepreferably 0.0005 to 1 mass % based on the total mass of the compositionof the present invention (excluding the solvent).

On the other hand, when the amount of surfactant added is controlled at10 ppm or less based on the whole amount (excluding the solvent) of theresist composition, the uneven distribution of the hydrophobic resin inthe surface portion is promoted, so that the surface of the resist filmcan be rendered highly hydrophobic, thereby enhancing the water trackingproperty in the stage of liquid-immersion exposure.

[3-7] Basic Compound or Compound (H) Whose Basicity is Increased by theAction of an Acid

The composition of the present invention preferably contains at leastone compound (H) selected from a basic compound and a compound whosebasicity is increased by the action of an acid so as to decrease anyperformance alteration over time from exposure to heating.

As preferred basic compounds, there can be mentioned the compoundshaving the structures of the following formulae (A) to (E).

In the general formulae (A) and (E),

R²⁰⁰, R²⁰¹ and R²⁰² may be identical to or different from each other andeach represent a hydrogen atom, an alkyl group (preferably having 1 to20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbonatoms) or an aryl group (having 6 to 20 carbon atoms). R²⁰¹ and R²⁰² maybe bonded with each other to thereby form a ring. R²⁰³, R²⁰⁴, R²⁰⁵ andR²⁰⁶ may be identical to or different from each other and each representan alkyl group having 1 to 20 carbon atoms.

With respect to the above alkyl group, as a preferred substituted alkylgroup, there can be mentioned an aminoalkyl group having 1 to 20 carbonatoms, a hydroxyalkyl group having 1 to 20 carbon atoms or a cyanoalkylgroup having 1 to 20 carbon atoms.

More preferably, in these general formulae (A) and (E) the alkyl groupis unsubstituted.

As preferred compounds, there can be mentioned guanidine,aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine,aminoalkylmorpholine, piperidine and the like. Further, as preferredcompounds, there can be mentioned compounds with an imidazole structure,a diazabicyclo structure, an onium hydroxide structure, an oniumcarboxylate structure, a trialkylamine structure, an aniline structureor a pyridine structure, alkylamine derivatives having a hydroxyl groupand/or an ether bond, aniline derivatives having a hydroxyl group and/oran ether bond and the like.

As the compounds with an imidazole structure, there can be mentionedimidazole, 2,4,5-triphenylimidazole, benzimidazole,2-phenylbenzoimidazole and the like. As the compounds with adiazabicyclo structure, there can be mentioned1,4-diazabicyclo[2,2,2]octane, 1,5-diazabicyclo[4,3,0]non-5-ene,1,8-diazabicyclo[5,4,0]undec-7-ene and the like. As the compounds withan onium hydroxide structure, there can be mentioned tetrabutylammoniumhydroxide, triarylsulfonium hydroxide, phenacylsulfonium hydroxide, andsulfonium hydroxides having a 2-oxoalkyl group such astriphenylsulfonium hydroxide, tris(t-butylphenyl)sulfonium hydroxide,bis(t-butylphenyl)iodonium hydroxide, phenacylthiophenium hydroxide,2-oxopropylthiophenium hydroxide and the like. As the compounds with anonium carboxylate structure, there can be mentioned those having acarboxylate at the anion moiety of the compounds with an onium hydroxidestructure, for example, acetate, adamantane-1-carboxylate,perfluoroalkyl carboxylate and the like. As the compounds with atrialkylamine structure, there can be mentioned tri(n-butyl)amine,tri(n-octyl)amine and the like. As the aniline compounds, there can bementioned 2,6-diisopropylaniline, N,N-dimethylaniline,N,N-dibutylaniline, N,N-dihexylaniline and the like. As the alkylaminederivatives having a hydroxyl group and/or an ether bond, there can bementioned ethanolamine, diethanolamine, triethanolamine,N-phenyldiethanolamine, tris(methoxyethoxyethyl)amine and the like. Asthe aniline derivatives having a hydroxyl group and/or an ether bond,there can be mentioned N,N-bis(hydroxyethyl)aniline and the like.

As preferred basic compounds, there can be further mentioned an aminecompound having a phenoxy group, an ammonium salt compound having aphenoxy group, an amine compound having a sulfonic ester group and anammonium salt compound having a sulfonic ester group.

Each of the above amine compound having a phenoxy group, ammonium saltcompound having a phenoxy group, amine compound having a sulfonic estergroup and ammonium salt compound having a sulfonic ester grouppreferably has at least one alkyl group bonded to the nitrogen atomthereof. Further preferably, the alkyl group in its chain contains anoxygen atom, thereby forming an oxyalkylene group. The number ofoxyalkylene groups in each molecule is one or more, preferably 3 to 9and more preferably 4 to 6. Oxyalkylene groups having the structure of—CH₂CH₂O—, —CH(CH₃)CH₂O— or —CH₂CH₂CH₂O— are preferred.

As specific examples of the above amine compound having a phenoxy group,ammonium salt compound having a phenoxy group, amine compound having asulfonic ester group and ammonium salt compound having a sulfonic estergroup, there can be mentioned the compounds (C1-1) to (C3-3) shown asexamples in Section [0066] of US 2007/0224539 A, which are howevernonlimiting.

The molecular weight of compound (H) is preferably 250 to 2000, morepreferably 400 to 1000.

Compound (H) may be used either individually or in combination.

When the composition contains compound (H), the content of compound (H)is preferably in the range of 0.05 to 8.0 mass %, more preferably 0.05to 5.0 mass % and most preferably 0.05 to 4.0 mass % based on the totalsolids of the composition.

With respect to the ratio of the acid generator to compound (H) used inthe composition, preferably, the acid generator/compound (H) (molarratio)=2.5 to 300. The reason for this is that the molar ratio ispreferred to be 2.5 or higher from the viewpoint of sensitivity andresolving power. The molar ratio is preferred to be 300 or below fromthe viewpoint of the inhibition of any resolving power deterioration dueto thickening of resist pattern over time from exposure to heatingtreatment. The acid generator/compound (H) (molar ratio) is morepreferably in the range of 5.0 to 200, still more preferably 7.0 to 150.

[3-8] Basic Compound and Ammonium Salt Compound that when Exposed toActinic Rays or Radiation, Exhibit Lowered Basicity

The resist composition of the present invention may contain a basiccompound or ammonium salt compound that when exposed to actinic rays orradiation, exhibits a lowered basicity (hereinafter also referred to asa “compound (PA)”). Namely, the compound (PA) is a compound that whenexposed to actinic rays or radiation, undergoes a change of chemicalstructure, exhibiting photosensitivity.

It is preferred for the compound (PA) to be a compound (PA′) containinga basic functional group or ammonium group and a group that when exposedto actinic rays or radiation, produces an acid functional group. Namely,it is preferred for the compound (PA) to be a basic compound containinga basic functional group and a group that when exposed to actinic raysor radiation, produces an acid functional group, or an ammonium saltcompound containing an ammonium group and a group that when exposed toactinic rays or radiation, produces an acid functional group.

As the compounds each exhibiting a lowered basicity, produced by thedecomposition of compound (PA) or compound (PA′) upon exposure toactinic rays or radiation, there can be mentioned the compounds ofgeneral formulae (PA-I), (PA-II) and (PA-III) below. The compounds ofgeneral formulae (PA-II) and (PA-III) are especially preferred from theviewpoint of the higher-order simultaneous attainment of excellenteffects concerning LWR and DOF.

First, the compounds of general formula (PA-I) will be described.Q-A₁-(X)n-B—R  (PA-I)

In general formula (PA-I),

A₁ represents a single bond or a bivalent connecting group.

Q represents —SO₃H or —CO₂H. Q corresponds to the acid functional groupproduced upon exposure to actinic rays or radiation.

X represents —SO₂— or —CO—.

n is 0 or 1.

B represents a single bond, an oxygen atom or —N(Rx)—.

Rx represents a hydrogen atom or a monovalent organic group.

R represents a monovalent organic group containing a basic functionalgroup or a monovalent organic group containing an ammonium group.

The bivalent connecting group represented by A₁ is preferably a bivalentconnecting group having 2 to 12 carbon atoms. As such, there can bementioned, for example, an alkylene group, a phenylene group or thelike. An alkylene group containing at least one fluorine atom is morepreferred, which has preferably 2 to 6 carbon atoms, more preferably 2to 4 carbon atoms. A connecting group, such as an oxygen atom or asulfur atom, may be introduced in the alkylene chain. In particular, analkylene group, 30 to 100% of the hydrogen atoms of which aresubstituted with fluorine atoms, is preferred. It is more preferred forthe carbon atom bonded to the Q-moiety to have a fluorine atom. Further,perfluoroalkylene groups are preferred. A perfluoroethylene group, aperfluoropropylene group and a perfluorobutylene group are morepreferred.

The monovalent organic group represented by Rx preferably has 4 to 30carbon atoms. As such, there can be mentioned, for example, an alkylgroup, a cycloalkyl group, an aryl group, an aralkyl group, an alkenylgroup or the like.

A substituent may be introduced in the alkyl group represented by Rx.The alkyl group is preferably a linear or branched alkyl group having 1to 20 carbon atoms. An oxygen atom, a sulfur atom or a nitrogen atom maybe introduced in the alkyl chain.

As the substituted alkyl group, in particular, there can be mentioned alinear or branched alkyl group substituted with a cycloalkyl group (forexample, an adamantylmethyl group, an adamantylethyl group, acyclohexylethyl group, a camphor residue, or the like).

A substituent may be introduced in the cycloalkyl group represented byRx. The cycloalkyl group preferably has 3 to 20 carbon atoms. An oxygenatom may be introduced in the ring.

A substituent may be introduced in the aryl group represented by Rx. Thearyl group preferably has 6 to 14 carbon atoms.

A substituent may be introduced in the aralkyl group represented by Rx.The aralkyl group preferably has 7 to 20 carbon atoms.

A substituent may be introduced in the alkenyl group represented by Rx.For example, there can be mentioned groups each resulting from theintroduction of a double bond at an arbitrary position of any of thealkyl groups mentioned above as being represented by Rx.

As preferred partial structures of the basic functional groups, therecan be mentioned, for example, the structures of a crown ether, aprimary to tertiary amine and a nitrogenous heterocycle (pyridine,imidazole, pyrazine or the like).

As preferred partial structures of the ammonium groups, there can bementioned, for example, the structures of a primary to tertiaryammonium, pyridinium, imidazolinium, pyrazinium and the like.

The basic functional group is preferably a functional group containing anitrogen atom, more preferably a structure having a primary to tertiaryamino group or a nitrogenous heterocyclic structure. In thesestructures, from the viewpoint of basicity increase, it is preferred forall the atoms adjacent to the nitrogen atom contained in each of thestructures to be carbon atoms or hydrogen atoms. Further, from theviewpoint of basicity increase, it is preferred to avoid the directbonding of electron-withdrawing functional groups (a carbonyl group, asulfonyl group, a cyano group, a halogen atom, etc.) to nitrogen atoms.

With respect to the monovalent organic group (R-group) containing any ofthese structures, the monovalent organic group preferably has 4 to 30carbon atoms. As such, there can be mentioned an alkyl group, acycloalkyl group, an aryl group, an aralkyl group, an alkenyl group orthe like. A substituent may be introduced in each of these groups.

The alkyl group, cycloalkyl group, aryl group, aralkyl group and alkenylgroup contained in the alkyl group, cycloalkyl group, aryl group,aralkyl group and alkenyl group each containing a basic functional groupor an ammonium group, represented by R are the same as the alkyl group,cycloalkyl group, aryl group, aralkyl group and alkenyl group set forthabove as being represented by Rx.

As substituents that may be introduced in these groups, there can bementioned, for example, a halogen atom, a hydroxyl group, a nitro group,a cyano group, a carboxyl group, a carbonyl group, a cycloalkyl group(preferably 3 to 10 carbon atoms), an aryl group (preferably 6 to 14carbon atoms), an alkoxy group (preferably 1 to 10 carbon atoms), anacyl group (preferably 2 to 20 carbon atoms), an acyloxy group(preferably 2 to 10 carbon atoms), an alkoxycarbonyl group (preferably 2to 20 carbon atoms), an aminoacyl group (preferably 2 to 20 carbonatoms) and the like. Further, with respect to the ring structure of thearyl group, cycloalkyl group, etc., an alkyl group (preferably 1 to 20carbon atoms, more preferably 1 to 10 carbon atoms) can be mentioned asa substituent. Further, with respect to the aminoacyl group, one or twoalkyl groups (each preferably 1 to 20 carbon atoms, more preferably 1 to10 carbon atoms) can be mentioned as substituents. As the substitutedalkyl groups, there can be mentioned, for example, perfluoroalkylgroups, such as a perfluoromethyl group, a perfluoroethyl group, aperfluoropropyl group and a perfluorobutyl group.

When B is —N(Rx)—, it is preferred for R and Rx to be bonded to eachother to thereby form a ring. When a ring structure is formed, thestability thereof is enhanced, and thus the storage stability of thecomposition containing the same is enhanced. The number of carbon atomsconstituting the ring is preferably in the range of 4 to 20. The ringmay be monocyclic or polycyclic, and an oxygen atom, a sulfur atom or anitrogen atom may be introduced in the ring.

As the monocyclic structure, there can be mentioned a 4- to 8-memberedring containing a nitrogen atom, or the like. As the polycyclicstructure, there can be mentioned structures each resulting from acombination of two, three or more monocyclic structures. Substituentsmay be introduced in the monocyclic structure and polycyclic structure.As preferred substituents, there can be mentioned, for example, ahalogen atom, a hydroxyl group, a cyano group, a carboxyl group, acarbonyl group, a cycloalkyl group (preferably 3 to 10 carbon atoms), anaryl group (preferably 6 to 14 carbon atoms), an alkoxy group(preferably 1 to 10 carbon atoms), an acyl group (preferably 2 to 15carbon atoms), an acyloxy group (preferably 2 to 15 carbon atoms), analkoxycarbonyl group (preferably 2 to 15 carbon atoms), an aminoacylgroup (preferably 2 to 20 carbon atoms) and the like. Further, withrespect to the ring structure of the aryl group, cycloalkyl group, etc.,an alkyl group (preferably 1 to 15 carbon atoms) can be mentioned as asubstituent. Further, with respect to the aminoacyl group, one or morealkyl groups (each preferably 1 to 15 carbon atoms) can be mentioned assubstituents.

Among the compounds of general formula (PA-1), the compounds wherein theQ-moiety is sulfonic acid can be synthesized by using a commonsulfonamidation reaction. For example, these compounds can besynthesized by a method in which one sulfonyl halide moiety of abissulfonyl halide compound is caused to selectively react with an aminecompound to thereby form a sulfonamido bond and thereafter the othersulfonyl halide moiety is hydrolyzed, or alternatively by a method inwhich a cyclic sulfonic anhydride is caused to react with an aminecompound to thereby effect a ring opening.

Now, the compounds of general formula (PA-II) will be described.Q₁-X₁—NH—X₂-Q₂  (PA-II)

In general formula (PA-II),

each of Q₁ and Q₂ independently represents a monovalent organic group,provided that either Q₁ or Q₂ contains a basic functional group. Q₁ andQ₂ may be bonded to each other to thereby form a ring, the ringcontaining a basic functional group.

Each of X₁ and X₂ independently represents —CO— or —SO₂—.

In the formula, —NH— corresponds to the acid functional group producedupon exposure to actinic rays or radiation.

The monovalent organic group represented by each of Q₁ and Q₂ in generalformula (PA-II) preferably has 1 to 40 carbon atoms. As such, there canbe mentioned, for example, an alkyl group, a cycloalkyl group, an arylgroup, an aralkyl group, an alkenyl group or the like.

A substituent may be introduced in the alkyl group represented by eachof Q₁ and Q₂. The alkyl group is preferably a linear or branched alkylgroup having 1 to 30 carbon atoms. An oxygen atom, a sulfur atom or anitrogen atom may be introduced in the alkyl chain.

A substituent may be introduced in the cycloalkyl group represented byeach of Q₁ and Q₂. The cycloalkyl group preferably has 3 to 20 carbonatoms. An oxygen atom or a nitrogen atom may be introduced in the ring.

A substituent may be introduced in the aryl group represented by each ofQ₁ and Q₂. The aryl group preferably has 6 to 14 carbon atoms.

A substituent may be introduced in the aralkyl group represented by eachof Q₁ and Q₂. The aralkyl group preferably has 7 to 20 carbon atoms.

A substituent may be introduced in the alkenyl group represented by eachof Q₁ and Q₂. For example, there can be mentioned groups each resultingfrom the introduction of a double bond at an arbitrary position of anyof the above alkyl groups.

As substituents that may be introduced in these groups, there can bementioned those set forth above by way of example as being introduciblein the groups of general formula (PA-I).

As preferred partial structures of the basic functional groups containedin at least either Q₁ or Q₂, there can be mentioned those describedabove as the basic functional groups contained in R of general formula(PA-I).

As the structure in which Q₁ and Q₂ are bonded to each other to therebyform a ring, the ring containing a basic functional group, there can bementioned, for example, a structure in which the organic groupsrepresented by Q₁ and Q₂ are bonded to each other by an alkylene group,an oxy group, an imino group or the like.

In general formula (PA-II), it is preferred for at least one of X₁ andX₂ to be —SO₂—.

Below, the compounds of general formula (PA-III) will be described.Q₁-X₁—NH—X₂-A₂-(X₃)_(m)—B-Q₃  (PA-III)

In general formula (PA-III),

each of Q₁ and Q₃ independently represents a monovalent organic group,provided that either Q₁ or Q₃ contains a basic functional group. Q₁ andQ₃ may be bonded to each other to thereby form a ring, the ringcontaining a basic functional group.

Each of X₁, X₂ and X₃ independently represents —CO— or —SO₂—.

A₂ represents a bivalent connecting group.

B represents a single bond, an oxygen atom or —N(Qx)-.

Qx represents a hydrogen atom or a monovalent organic group.

When B is —N(Qx)-, Q₃ and Qx may be bonded to each other to thereby forma ring.

m is 0 or 1.

In the formula, —NH— corresponds to the acid functional group producedupon exposure to actinic rays or radiation.

Q₁ has the same meaning as that of Q₁ of general formula (PA-II).

As the organic groups represented by Q₃, there can be mentioned thoseset forth above as being represented by Q₁ and Q₂ of general formula(PA-II).

The bivalent connecting group represented by A₂ is preferably a bivalentconnecting group having 1 to 8 carbon atoms in which a fluorine atom isintroduced. As such, there can be mentioned, for example, an alkylenegroup having 1 to 8 carbon atoms in which a fluorine atom is introduced,a phenylene group in which a fluorine atom is introduced, or the like.An alkylene group containing a fluorine atom is more preferred, whichhas preferably 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms.A connecting group, such as an oxygen atom or a sulfur atom, may beintroduced in the alkylene chain. In particular, an alkylene group, 30to 100% of the hydrogen atoms of which are substituted with fluorineatoms, is preferred. Further, perfluoroalkylene groups are preferred.Perfluoroalkylene groups each having 2 to 4 carbon atoms are mostpreferred.

The monovalent organic group represented by Qx preferably has 4 to 30carbon atoms. As such, there can be mentioned, for example, an alkylgroup, a cycloalkyl group, an aryl group, an aralkyl group, an alkenylgroup or the like. As the alkyl group, cycloalkyl group, aryl group,aralkyl group and alkenyl group, there can be mentioned those set forthabove as being represented by Rx of general formula (PA-I).

In general formula (PA-III), it is preferred for each of X₁, X₂ and X₃to be —SO₂—.

The compounds (PA) are preferably sulfonium salt compounds from thecompounds of general formulae (PA-I), (PA-II) and (PA-III) and iodoniumsalt compounds from the compounds of general formulae (PA-I), (PA-II)and (PA-III), more preferably the compounds of general formulae (PA1)and (PA2) below.

In general formula (PA1),

each of R₂₀₁, R₂₀₂ and R₂₀₃ independently represents an organic group.In particular, these are the same as R₂₀₁, R₂₀₂ and R₂₀₃ of formula ZImentioned above in connection with the acid generator.

X⁻ represents a sulfonate anion or carboxylate anion resulting from thecleavage of a hydrogen atom from the —SO₃H moiety or —COOH moiety ofeach of the compounds of general formula (PA-I), or an anion resultingfrom the cleavage of a hydrogen atom from the —NH— moiety of each of thecompounds of general formulae (PA-II) and (PA-III).

In general formula (PA2) above,

each of R₂₀₄ and R₂₀₅ independently represents an aryl group, an alkylgroup or a cycloalkyl group. In particular, these are the same as R₂₀₄and R₂₀₅ of formula ZII mentioned above in connection with the acidgenerator.

X⁻ represents a sulfonate anion or carboxylate anion resulting from thecleavage of a hydrogen atom from the —SO₃H moiety or —COOH moiety ofeach of the compounds of general formula (PA-I), or an anion resultingfrom the cleavage of a hydrogen atom from the —NH— moiety of each of thecompounds of general formulae (PA-II) and (PA-III).

The compounds (PA) when exposed to actinic rays or radiation aredecomposed to thereby produce, for example, the compounds of generalformulae (PA-I), (PA-II) and (PA-III).

Each of the compounds of general formula (PA-I) contains a sulfonic acidgroup or a carboxylic acid group together with a basic functional groupor an ammonium group, so that it is a compound having its basicitylowered as compared with that of the compound (PA) or dissipated, orhaving its basicity converted to acidity.

Each of the compounds of general formulae (PA-II) and (PA-III) containsan organic sulfonylimino group or an organic carbonylimino grouptogether with a basic functional group, so that it is a compound havingits basicity lowered as compared with that of the compound (PA) ordissipated, or having its basicity converted to acidity.

In the present invention, the lowering of basicity upon exposure toactinic rays or radiation means that the acceptor properties for theproton (acid produced by exposure to actinic rays or radiation) of thecompound (PA) are lowered by exposure to actinic rays or radiation. Thelowering of acceptor properties means that when an equilibrium reactionin which a noncovalent-bond complex being a proton adduct is formed froma proton and a compound containing a basic functional group occurs, orwhen an equilibrium reaction in which the counter cation of a compoundcontaining an ammonium group is replaced by a proton occurs, theequilibrium constant of the chemical equilibrium is lowered.

When the compound (PA) whose basicity is lowered upon exposure toactinic rays or radiation is contained in the resist film, in nonexposedareas, the acceptor properties of the compound (PA) are fully exhibited,so that any unintended reaction between the acid diffused from exposedareas, etc. and the resin (A) can be suppressed. In exposed areas, theacceptor properties of the compound (PA) are lowered, so that theintended reaction between the acid and the resin (A) occurs with highcertainty. It is presumed that, by virtue of the contribution of thisactivity mechanism, a pattern excelling in line width roughness (LWR),focus latitude (depth of focus DOF) and pattern shape can be obtained.

The basicity can be ascertained by performing pH measurement. Also,calculated values of basicity can be obtained by utilizing commerciallyavailable software.

As particular examples of the compounds (PA) whose basicity is loweredupon exposure to actinic rays or radiation, there can be mentioned, forexample, those described in JP-A-2006-208781 and JP-A-2006-330098.

Particular examples of the compounds (PA) that produce the compounds ofgeneral formula (PA-I) upon exposure to actinic rays or radiation areshown below, which in no way limit the scope of the present invention.

These compounds can be easily synthesized from the compounds of generalformula (PA-I), or a lithium, sodium or potassium salt thereof, and ahydroxide, bromide or chloride of iodonium or sulfonium, etc. by thesalt exchange method described in Jpn. PCT National Publication No.H11-501909 and JP-A-2003-246786. Also, the synthesis can be performed inaccordance with the method described in JP-A-H7-333851.

Particular examples of the compounds (PA) that produce the compounds ofgeneral formulae (PA-II) and (PA-III) upon exposure to actinic rays orradiation are shown below, which in no way limit the scope of thepresent invention.

These compounds can be synthesized by, for example, the method describedin JP-A-2006-330098.

The molecular weight of each of the compounds (PA) is preferably in therange of 500 to 1000.

When the resist composition of the present invention contains any of thecompounds (PA), the content thereof based on the solids of thecomposition is preferably in the range of 0.1 to 20 mass %, morepreferably 0.1 to 10 mass %.

Any of the compounds (PA) may be used alone, or two or more thereof maybe used in combination. The compounds (PA) may be used in combinationwith the above-mentioned basic compounds.

[3-9] Other Additive

The resist composition of the present invention according to necessitycan further be loaded with a dye, a plasticizer, a photosensitizer, alight absorber, a dissolution inhibitor, a dissolution accelerator, etc.

The total solid content of the resist composition of the presentinvention is generally in the range of 1.0 to 10 mass %, preferably 2.0to 5.7 mass % and more preferably 2.0 to 5.3 mass %. When the solidcontent falls within the above range, the resist solution can beuniformly applied onto a substrate, and a resist pattern excelling inline edge roughness can be formed. The reason therefor has not beenelucidated but is presumed to be that when the solid content is 10 mass% or less, preferably 5.7 mass % or less, the aggregation of materials,especially the photoacid generator, contained in the resist solution canbe suppressed with the result that a uniform resist film can be formed.

The solid content refers to the percentage of the mass of resistcomponents other than the solvent in the total mass of the resistcomposition.

The present invention will be described in greater detail below by wayof its examples. However, the present invention is in no way limited tothese examples.

[Preparation of Resist]

Solutions each of 6 mass % solid content were prepared using thecomponents of Table 2 below. The solutions were each passed through a0.03 μm polyethylene filter. Thus, resist compositions were obtained.

TABLE 2 Comp. (a) (b) (c) (d) (e) (f) Ar-01 Resin(1) PAG-1 TPI W-1 (1b)A1/B1 (10) (0.8) (0.03) (0.03) (0.05) (70/30) Ar-02 Resin(2) PAG-2 TPIW-1 (1b) A1/A3 (10) (0.7) (0.03) (0.03) (0.05) (80/20)

In Table 2, (a) signifies a resin (A) (mass/g); (b) signifies an acidgenerator (mass/g); (c) signifies a basic compound (mass/g); (d)signifies a surfactant (mass/g); (e) signifies a resin (B) (mass/g); and(f) signifies a solvent (mass ratio). The meanings of the abbreviationsused in Table 2 are as follows.

<Resin (A)>

<Resin (B)>

The following resin (1b) was provided as the resin (B).

With respect to each of the resins, the component ratio (molar ratio) ofrepeating units, weight average molecular weight and dispersity (Pd) aregiven in Table 3 below.

TABLE 3 Resin (1) (2) (1b) Comp. 50/40/10 40/50/10 30/60/10 Molecularweight 10000 12000 5000 Pd 1.68 1.76 1.40

<Acid Generator>

<Basic Compound>

TPI: 2,4,5-triphenylimidazole.

<Surfactant>

W-1: PF6320 (produced by OMNOVA SOLUTIONS, INC.).

<Solvent>

A1: propylene glycol monomethyl ether acetate,

A2: γ-butyrolactone,

A3: cyclohexanone,

B1: propylene glycol monomethyl ether, and

B2: ethyl lactate.

[Formation of Resist Pattern]

An organic antireflection film ARC29A (produced by Nissan ChemicalIndustries, Ltd.) was applied onto a silicon wafer and baked at 205° C.for 60 seconds, thereby forming a 86 nm-thick antireflection film. Eachof the prepared resist compositions was applied thereonto and baked at100° C. for 60 seconds (PreBake; PB), thereby forming a 100 nm-thickresist film. The resultant wafer was patternwise exposed by means of anArF excimer laser scanner (NA0.75). Thereafter, the exposed wafer wasbaked at 100° C. for 60 seconds (Post-Exposure Bake, PEB). The thusbaked wafer was developed with the below-identified developer for 30seconds, rinsed with the below-identified rinse liquid and rotated at arotating speed of 4000 rpm for 30 seconds. Thus, (1:1) line-and-spacepatterns of 75 nm line width were obtained.

[Developer and Rinse Liquid]

Each of the developers and rinse liquids was subjected to an appropriatecombination of the following processings.

(Processing 1: Filtration)

In an ordinary laboratory environment, a commercially available chemicalof electronic material grade was passed through a polyethylene filter of0.03 μm pore size, and placed and stored in a bloomed clean bottle.

(Processing 2: Class 1000 Environment)

In a class 1000 environment, a commercially available chemical ofelectronic material grade was passed through a polyethylene filter of0.03 μm pore size, and placed and stored in a bloomed clean bottle.

(Processing 3: Class 100 Environment)

In a class 100 environment, a commercially available chemical ofelectronic material grade was passed through a polyethylene filter of0.03 μm pore size, and placed and stored in a bloomed clean bottle.

Tables 4 and 5 below give a summary of the developers and rinse liquidsemployed in the Examples and Comparative Examples. In the tables, “o”signifies having carried out the relevant processing, and “x” signifiesnot having carried out the relevant processing.

With respect to each of the developers and rinse liquids, the density ofparticles each having a diameter of 0.3 μm or greater was measured bymeans of an in-liquid particle sensor KS-41A (manufactured by Rion Co.,Ltd.). This measurement was carried out in a class 1000 clean room at ameasuring flow rate of 10 ml/min. The results are also given in Tables 4and 5 below.

[Developer]

TABLE 4 Developer: butyl acetate Processing/quality (1-1) (1-2) (1-3)(1-4) Filtration x ∘ ∘ ∘ Class 1000 environ. x x ∘ x Class 100 environ.x x x ∘ Particle density (no./ml) 194 26 19 11 Developer: methyl amylketone Processing/quality (2-1) (2-2) (2-3) (2-4) Filtration x ∘ ∘ ∘Class 1000 environ. x x ∘ x Class 100 environ. x x x ∘ Particle density(no./ml 237 29 22 18 Developer: 3-ethoxypropionate Processing/quality(3-1) (3-2) (3-3) (3-4) Filtration x ∘ ∘ ∘ Class 1000 environ. x x ∘ xClass 100 environ. x x x ∘ Particle density (no./ml 218 25 18 13[Rinse liquid]

TABLE 5 Rinse liquid: 4-methyl-2-pentanol Processing/quality (4-1) (4-2)(4-3) (4-4) Filtration x ∘ ∘ ∘ Class 1000 environ. x x ∘ x Class 100environ. x x x ∘ Particle density (no./ml 189 31 19 14 Rinse liquid:decane Processing/quality (5-1) (5-2) (5-3) (5-4) Filtration x ∘ ∘ ∘Class 1000 environ. x x ∘ x Class 100 environ. x x x ∘ Particle density(no./ml 179 20 13 8

<Evaluation>

[Defect]

The optimum exposure amount and optimum focus were respectively definedas the exposure amount and focus that form a 1:1 line-and-space resistpattern of 75 nm line width. The number of defects of each patternobtained under the conditions of the optimum exposure amount and optimumfocus was digitized and evaluated on the following criteria. The resultsare given in Table 6 below.

⊚ (Excellent): 0 to 50 defects,

∘ (Good): 51 to 100 defects,

Δ (Fair): 101 to 150 defects, and

x (Insufficient): 151 or more defects.

TABLE 6 Resist Ar-01 Developer (1-1) (1-2) (1-3) (1-4) Rinse liquid(4-4) (4-4) (4-4) (4-4) Defect no. x Δ ∘ ∘ Resist Ar-02 Developer (2-1)(2-2) (2-3) (2-4) Rinse liquid (4-4) (4-4) (4-4) (4-4) Defect no. x Δ ∘∘ Resist Ar-01 Developer (3-1) (3-2) (3-3) (3-4) Rinse liquid (5-4)(5-4) (5-4) (5-4) Defect no. x ∘ ∘ ∘ Resist Ar-01 Developer (1-4) (1-4)(1-4) (1-4) Rinse liquid (4-1) (4-2) (4-3) (4-4) Defect no. ∘ ∘ ∘ ⊚Resist Ar-02 Developer (1-4) (1-4) (1-4) (1-4) Rinse liquid (5-1) (5-2)(5-3) (5-4) Defect no. ∘ ∘ ∘ ⊚ Resist Ar-02 Developer (1-1) (1-2) (1-3)(1-4) Rinse liquid — — — — Defect no. x Δ ∘ ∘

As apparent from Table 6, the number of defects could be strikinglyreduced by using the developer in which the density of particles eachhaving a diameter of 0.3 μm or greater is 30 particles/ml or less.

What is claimed is:
 1. A method of forming a pattern, comprising: (a)forming a chemically amplified resist composition into a film, (b)exposing the film to light, and (c) developing the exposed film with adeveloper containing a first organic solvent subjected to a distillingoperation, wherein in the developer, particles each having a diameter of0.3 μm or greater amount to a density of 30 particles/ml or less.
 2. Themethod according to claim 1, wherein the first organic solvent containedin the developer is one filled in a storage container in an environmentwhose cleanliness defined in US Federal Standard 209E is class 10,000 orbelow.
 3. The method according to claim 1, which further comprises: (d)rinsing the developed film by a rinse liquid containing a second organicsolvent, wherein in the rinse liquid, particles each having a diameterof 0.3 μm or greater amount to a density of 30 particles/ml or less. 4.The method according to claim 3, wherein the second organic solventcontained in the rinse liquid is one filled in a storage container in anenvironment whose cleanliness defined in US Federal Standard 209E isclass 10,000 or below.
 5. The method according to claim 1, wherein theexposure (b) is carried out using an ArF excimer laser.
 6. The methodaccording to claim 1, wherein the composition comprises a resincontaining a group that when acted on by an acid, is decomposed tothereby produce a polar group and a compound that when exposed toactinic rays or radiation, generates an acid.
 7. The method according toclaim 6, wherein the resin has an alicyclic hydrocarbon structure. 8.The method according to claim 6, wherein substantially no aromatic ringis contained in the resin.
 9. A method of forming a pattern, comprising:(a) forming a chemically amplified resist composition into a film, (b)exposing the film to light, and (c) developing the exposed film with adeveloper containing a first organic solvent, wherein in the developer,particles each having a diameter of 0.3 μm or greater amount to adensity of 30 particles/ml or less, and wherein the first organicsolvent is filled in a storage container having been rinsed with thefirst organic solvent and dried.
 10. The method according to claim 9,wherein the first organic solvent contained in the developer is onefilled in a storage container in an environment whose cleanlinessdefined in US Federal Standard 209E is class 10,000 or below.
 11. Themethod according to claim 9, which further comprises: (d) rinsing thedeveloped film by a rinse liquid containing a second organic solvent,wherein in the rinse liquid, particles each having a diameter of 0.3 μmor greater amount to a density of 30 particles/ml or less.
 12. Themethod according to claim 9, wherein the second organic solventcontained in the rinse liquid is one filled in a storage container in anenvironment whose cleanliness defined in US Federal Standard 209E isclass 10,000 or below.
 13. The method according to claim 9, wherein theexposure (b) is carried out using an ArF excimer laser.
 14. The methodaccording to claim 9, wherein the composition comprises a resincontaining a group that when acted on by an acid, is decomposed tothereby produce a polar group and a compound that when exposed toactinic rays or radiation, generates an acid.
 15. The method accordingto claim 9, wherein the resin has an alicyclic hydrocarbon structure.16. The method according to claim 9, wherein substantially no aromaticring is contained in the resin.
 17. A method of forming a pattern,comprising: (a) forming a chemically amplified resist composition into afilm, (b) exposing the film to light, and (c) developing the exposedfilm with a developer containing a first organic solvent that is methylamyl ketone, wherein in the developer, particles each having a diameterof 0.3 μm or greater amount to a density of 30 particles/ml or less. 18.A method of forming a pattern, comprising: (a) forming a chemicallyamplified resist composition into a film, (b) exposing the film tolight, and (c) developing the exposed film with a developer containing afirst organic solvent, and (d) rinsing the developed film by a rinseliquid containing a second organic solvent that is 4-methyl-2-pentanol,wherein in the developer, particles each having a diameter of 0.3 μm orgreater amount to a density of 30 particles/ml or less.